Compounding a felony means that someone has done something wrong and someone else knows about it, but instead of telling the police or other authorities, they decide to keep it a secret or try to help the person who did the wrong thing. This is not allowed and it is against the law.
Think of it like this: You have a friend who took someone else's toy without asking. You know they did something wrong, but instead of telling the teacher, you decide to help them hide the toy or make up a story to cover it up. That's like compounding a felony.
It's important to tell the truth and help authorities when someone has done something wrong, so they can try to make things right and keep everyone safe. If you compound a felony, you can get in trouble too for not doing the right thing.