So, imagine that you are playing a game of cops and robbers with your friends. Jonathan Wild was like a really bad guy who played that game in real life, but not for fun. He was a robber himself, but he also helped other robbers steal things and then he would take some of the stolen things for himself.
But wait, it gets worse. Not only was he a robber, but he was also a snitch. That means he would tell on his fellow robbers to the police and get them arrested or even killed. And, the police would pay him for the information!
So, Jonathan Wild was basically a bad guy who pretended to help the police while also being a robber himself. But eventually, the police caught onto his tricks, and he was arrested and punished for his crimes.