Why do we use 'conjugaison' in French?
Once upon a time the French language originated from a Old French, and the Old French from Latin, and the Latin from a language more ancient…..
So that languages had conjugation (of verbs) and even declension (of other words) and cases (of nouns)… Only conjugations remain in Modern French.
The conjugation is used for determination of acting person and time.
Now there isn't any difference between 1sing, 2sing, 3sing and 3plural person form of some verbs in oral speech (for example je parle, tu parles, il parle, ils parlent… parle/-es/-ent sound equally) but we can write it according to French grammar (which originated many year ago).
Look, most of the indoeuropean languages have conjugation. For example if we examine such languages like Spanish: I speak – yo hablo, you speak – tu hablas, italian, greek,…
The verb endings allow you to know who you are talking about and when. However there is usually the pronoun which also indicates the same thing, or else the subjet.
Nous avons une maison : we speak about 'nous' and 'now'.
Jacques et Paul avaient une maison : we speak about 'Jacques et Paul, ils' and 'before', past time.
If you don't have the subject, you can find it only with the end of the verb.
You will learn that there are different "types" of French verbs, those ending with -er, -re, -ir etc.