A tense is a grammatical feature that enable to place a fact (which can either be a state of being or an action) in the enunication time axis regarding three benchmarks: the past, the present and the future. Those can also be divided.
The tenses in French are extremely important because they are closely linked to the conjugation of the verbs. You will discern if a an action happens in the past or the future depending on conjugation of the verb.
Each tense has its own rules for the conjugation of the verbs, and they are visible with the endings of the verbs.
The verbs are divided in 3 different groups. The first two groups have regular conjugation for each tense, whereas the third group gathers all the remaining irregular verbs.
Hence, it’s essential to master the conjugation rules of each tense to be able to speak French fluently.