Okay kiddo, imagine that you have a group of grown-ups who are in charge of making sure that everyone plays fairly and follows the rules. That group of grown-ups is kind of like the public prosecutor's office in Brazil.
Their job is to investigate crimes and decide if there is enough evidence to take someone to court. If they think there is, they will go to court and try to prove that the person is guilty of breaking the law.
Now, let's say that someone is accused of stealing a toy from another kid. The public prosecutor's office would look at all the evidence, like witnesses and security camera footage, to see if they think the person did it. If they do, they will take that person to court and try to get them in trouble for stealing.
The public prosecutor's office is really important because they help keep everyone safe and make sure that people who break the law are held responsible for their actions.