A Mitzvah (or Mitzvot in plural) is a commandment or a ritual.
Mitzvot are divided into two categories: Mitzvot of a positive nature (must do) and Mitzvot
of a negative nature or restrictions (must not do).
There are 248 must-do Mitzvot and 365 Mitzvot that are must-not-do. In total, there are 613 Mitzvot in Judaism. Each and every Mitzvah has specific details how it should be done properly.
In fact, no Jew has to actually perform all 613 Mitzvot. Some are just for men, some are just for women, some are just for priests (Kohanim), some are occupation or business
related, some are to be performed only on a specific time or occasion.
Some of the Mitzvot are relevant to all Jews.
The reward for fulfilling the Mitzvot - must-do and must-not-do - is unknown. There is a reward in this world, but the significant reward is in the world of spirituality, after the soul leaves the body and goes back to the 'spiritual world'.
The value of each Mitzvah (or the punishment for breaking the law) is unknown. We don't know which Mitzvah has more value, which Mitzvah is more important. We are commanded to perform all rituals and Mitzvot with the same level of passion and excitement.