The Finnish language does not distinguish gender in nouns or even in personal pronouns: hän is 'he', 'she' or 'it' depending on the referring party. There are no articles, neither definite nor indefinite. Thus, to get an accurate translation, context is often needed.
Finnish has fifteen noun cases: four grammatical cases, six locative cases, two essive cases (three in some Eastern dialects) and three marginal cases.
As in other Uralic languages, locative cases in Finnish can be classified according to three criteria: the spatial position (interior or surface), the motion status (stationary or moving), and within the latter, the direction of the movement (approaching or departing).
There are three different plurals in Finnish: nominative, the form used after numerals, inflected plural. After numerals greater than one in the nominative singular, the noun is put in the partitive (one of the cases) singular. Otherwise, the noun and the numeral agree with each other in number and case.
Adjectives in Finnish are inflected in exactly the same way nouns are, and an adjective must agree in number and case with the noun it is modifying. For example:
iso - big
iso(n) talo(n) edessä - in front of the big house
The comparative of the adjective is formed by adding -mpi to the inflecting stem.
isompi - bigger
The superlative of the adjective is formed by adding -in to the inflecting stem.
isolin - biggest
A very common way of forming adverbs is by adding the ending -sti to the inflecting form of the corresponding adjective.
helppo, helposti - easy, easily
The comparative form of the adverb has the ending -mmin. The superlative form of the adverb has the ending -immin.
helpommin - more easily
helpoimmin - most easily
There are personal (minä, hän), demonstrative (tämä, tuo), interrogative (kuka, mikä), relative (joka), reciprocal (toinen), reflexive (itse), and indefinite (jokin, kukin) pronouns in the Finnish language.
The pronouns are inflected much in the same way that their referring nouns are.
Finnish verbs are usually divided into seven groups depending on the stem type. All seven types have the same set of endings, but the stems undergo (slightly) different changes when inflected. There are very few irregular verbs in Finnish.
Finnish does not have a separate verb for possession (compare English «to have»). Possession is indicated in other ways, mainly by genitives and existential clauses.
koiralla on häntä - the dog has a tail (literally «on the dog is a tail», or in English grammar, «There is a tail on the dog»)
Finnish verbs have present, imperfect, perfect and pluperfect tense-aspect forms:
Finnish has two possible verb voices: active and passive. The active voice corresponds with the active voice of English, but the Finnish passive voice has some important differences from the English passive voice.
For instance, the Finnish passive is unipersonal, that is, it only appears in one form regardless of who is understood to be performing the action.
It can also be said that in the Finnish passive the agent is always human and never mentioned. A sentence such as «the tree was blown down» would translate poorly into Finnish if the passive were used, since it would suggest the image of a group of people trying to blow the tree down.
There are four moods in the Finnish language: indicative, imperative, conditional, and potential.
Since Finnish is an inflected language, word order within sentences can be much freer than, for example, English. In English, the strong subject–verb–object order typically indicates the function of a noun as either subject or object although some English structures allow this to be reversed. In Finnish sentences, however, the role of the noun is determined not by word order or sentence structure as in English but by case markings that indicate subject and object.
The most commonly used neutral order, however, is subject–verb–object. Usually what the speaker or writer is talking about is at the head of the sentence.
Postpositions are more common in Finnish than prepositions. Both postpositions and prepositions can be combined with either a noun or a possessive suffix to form a postpositional phrase.
Postpositions indicate place, time, cause, consequence or relation. In postpositional phrases, the noun is usually in the genitive.
pöydän alla - under the table
There are few important prepositions in Finnish. In prepositional phrases, the noun is always in the partitive.
ennen joula - before Christmas
Some postpositions can also be used as prepositions.
kylän keskellä, keskellä kylää - in the middle of the village
This is a very brief overview over the Finnish 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 Finnish grammatical system and the main points you should consider when learning.