Nouns in Literary Arabic have three grammatical cases (nominative, accusative, and genitive [also used when the noun is governed by a preposition]); three numbers (singular, dual and plural); two genders (masculine and feminine); and three "states" (indefinite, definite, and construct).
The cases of singular nouns (other than those that end in long ā) are indicated by suffixed short vowels (/-u/ for nominative, /-a/ for accusative, /-i/ for genitive).
Arabic distinguishes between nouns based on number. All nouns are singular, dual or plural. In Classical Arabic, the use of the dual is mandatory whenever exactly two objects are referred to, regardless of whether the "two-ness" of the objects is explicit or not.
For example, in a sentence like "I picked up my children from school yesterday and then helped them with their homework", the words "children", "them" and "their" must be in the dual if exactly two children are referred to, regardless of whether the speaker wants to make this fact explicit or not. This implies that when the plural is used, it necessarily implies three or more.
The grammatical property of state is specific to Arabic and other Semitic languages. The basic division is between definite and indefinite, corresponding approximately to English nouns preceded, respectively, by the definite article and the indefinite article.
That is to say that a definite noun signals either a particular entity previously referenced, a generic concept or proper nouns. Indefinite nouns refer to entities not previously mentioned.
The third value for state is construct. Nouns assume the construct state when they are definite and modified by another noun in a genitive construction.
The article الـ (al) is indeclinable and expresses the definite state of a noun of any gender and number.
The sound of the final -l consonant, can vary; when followed by a sun letter such as t, d, r, s, n, and a few others, it assimilates to that sound, thus doubling it. For example: for "the Nile", one does not say al-Nīl, but an-Nīl. When followed by a moon letter, like m-, there is no assimilation: al-masjid ("the mosque"). This affects only the pronunciation and not the spelling of the article.
Arabic has an indefinite article indicated by nunation (the addition of one of three vowel diacritics) which is declined for three cases.
Adjectives in Literary Arabic are marked for case, number, gender, and state, as for nouns. However, the plural of all non-human nouns is always combined with a singular feminine adjective.
Arabic adjectives must agree with the nouns in all respects.
Adverbials are expressed using adjectives in the indefinite accusative, often written with the ending ـًا (e.g. أَيْضًا ayḍan "also") but pronounced "-an" even if it isn’t spelled out:
قَرَأَ ٱلْكِتَابَ قِرَاءَةً بَطِيئَةً qaraʼa al-kitāba qirāʼatan baṭīʼatan - he read the book a slow reading; i.e., he read the book slowly
This type of construction is known as the "absolute accusative".
Adverbs can be formed from adjectives, ordinal numerals: كَثِيرًا kaṯīran "frequently, a lot, often", نَادِرًا nādiran "rarely", أَوَّلاً ʼawwalan "firstly" or from nouns: عَادَةً ʻādatan "usually", جِدًا ǧiddan "very".
The second method to form adverbs is to use a preposition and a noun, e.g. بِـ bi-, e.g. بِسُرْعَةٍ bi-surʻa(tin) "swift, with speed", بِٱلضَّبْطِ bi-ḍ-ḍabṭ(i) "exactly".
In Arabic, personal pronouns have 12 forms. In singular and plural, the 2nd and 3rd persons have separate masculine and feminine forms, while the 1st person does not. In the dual, there is no 1st person, and only a single form for each 2nd and 3rd person.
For all but the first person singular, the same forms are used regardless of the part of speech of the word attached to. In the first person singular, however, the situation is more complicated. Specifically, -nī "me" is attached to verbs, but -ī/-ya "my" is attached to nouns.
Arabic verbs, like the verbs in other Semitic languages, are extremely complex. Verbs in Arabic are based on a root made up of three or four consonants (called a triliteral or quadriliteral root, respectively). The set of consonants communicates the basic meaning of a verb, e.g. k-t-b 'write', q-r-’ 'read', ’-k-l 'eat'. Changes to the vowels in between the consonants, along with prefixes or suffixes, specify grammatical functions.
Verbs in Literary Arabic are marked for person (first, second, or third), gender, and number. They are conjugated in two major paradigms (past and non-past); two voices (active and passive); and six moods (indicative, imperative, subjunctive, jussive, shorter energetic and longer energetic), the fifth and sixth moods, the energetics, exist only in Classical Arabic but not in Modern Standard Arabic. There are also two participles (active and passive) and a verbal noun, but no infinitive.
The past and non-past paradigms are sometimes also termed perfective and imperfective, indicating the fact that they represent a combination of tense and aspect. The moods other than the indicative occur only in the non-past, and the future tense is signaled by prefixing سَـ sa- or سَوْفَ sawfa onto the non-past.
Since Arabic lacks an auxiliary verb "to have", constructions using li-, ‘inda, and ma‘a with the pronominal suffixes are used to describe possession:
عنده بيت (ʿindahu bayt) - literally: At him (is) a house - He has a house
Classical Arabic tends to prefer the word order VSO (verb before subject before object) rather than SVO (subject before verb before object). Verb initial word orders like in Classical Arabic are relatively rare across the world's languages, occurring only in a few language families including Celtic, Austronesian, and Mayan.
The alternation between VSO and SVO word orders in Arabic results in an agreement asymmetry: the verb shows person, number, and gender agreement with the subject in SVO constructions but only gender (and possibly person) agreement in VSO, to the exclusion of number.
There are two types of prepositions, based on whether they arise from the triconsonantal roots system or not. There are ten 'true prepositions' that do not stem from the triconsonantal roots. These true prepositions cannot have prepositions preceding them, in contrast to the derived triliteral prepositions.
True prepositions can also be used with certain verbs to convey a particular meaning. For example, بَحَثَ baḥatha means "to discuss" as a transitive verb but can mean "to search for" when followed by the preposition عَنْ ‘an, and "to do research about" when followed by فِي fī.
The prepositions arising from the triliteral root system are called "adverbs of place and time" in the native tradition and work very much in the same way as the 'true' prepositions.
A noun following a preposition takes the genitive case. However, prepositions can take whole clauses as their object too if succeeded by the conjunctions أَنْ ’an or أَنَّ ’anna, in which case the subject of the clause is in the nominative or the accusative respectively.
This is a very brief overview of Arabic grammar. To truly master it, you will need to study each of the parts of speech in much more detail. However, this overview will hopefully give you a general idea of the Arabic grammatical system and of the main points you should consider when learning.