Charles Ponzi was a man who promised to make people rich quickly and easily, but he wasn't exactly telling the truth. In fact, he was tricking people into giving him their money by promising to invest it in something that didn't exist or wasn't worth as much as he said it was.
Think of it like playing a game of pretend with your friends. You tell them you have a toy that they really want and then they give you their toy in exchange for yours. However, your toy was actually just a broken piece of junk and now you have their toy too.
People gave Ponzi their money in the hopes of making a lot of money back, but instead, he just used that money to pay off the earlier investors and keep some for himself. This is called a Ponzi scheme because he was using new money to pay off old debts, much like a game of hot potato where the money was constantly being passed around.
Eventually, the scheme collapsed when there weren't enough new investors to pay off the old ones, and Ponzi was caught and went to jail. So, it's important to be careful with your money and not believe everything someone tells you, especially if it sounds too good to be true.