Okay kiddo, imagine you and your friends are playing hide and seek. When it's your turn to be "it", you have to find all your friends who are hiding.
But what if someone breaks the rules and hides in a place they're not supposed to, or someone doesn't come out of hiding when they're found? That's where a prosecutor comes in.
A prosecutor is like a grown-up who makes sure everyone follows the rules when someone does something wrong. They work for the government and their job is to investigate and figure out if someone broke the law. If they think someone did break the law, they will take that person to court and try to prove that they did something wrong.
It's kind of like someone who makes sure everyone plays fair during the game of hide and seek. If someone doesn't play fair, the prosecutor will try to give them a consequence for not playing by the rules. This is important because it keeps everyone safe and fair, just like in a game of hide and seek.