The single most important French verb is être, to be. It's irregular, so each form simply has to be learned:

Pronoun	Être	English
je	suis	I am
tu	es	you are
il / elle / on	est	he / she is · we are (on)
nous	sommes	we are
vous	êtes	you are
ils / elles	sont	they are

Es (in tu es) and est (in il est) are spelt differently but sound the same — “eh” — because the final consonants are silent.