Repentance is when someone feels really bad about something wrong they have done and they want to make things right. It's like saying sorry and doing what you can to fix what went wrong.
Think about it like this - imagine you were playing with your friend's toy and accidentally broke it. You would feel bad and might cry because you knew you shouldn't have broken it. But then you decide to tell your friend you're sorry, maybe even give them one of your toys as a replacement, and promise to not break their things again.
That's what repentance is - feeling sorry, trying to make things better, and promising to do better in the future. It's important because when we make mistakes, it's not just about getting in trouble, but about recognizing we've hurt someone or something, and wanting to make up for it.