"Eye for an eye" is an old saying that means if someone hurts you, you can hurt them back in the same way.
It comes from a time when people thought it was fair to punish people in the same way they hurt others. For example, if someone poked someone else in the eye, they would get their eye poked back.
But nowadays, most people don't believe in hurting others to get revenge. Instead, we try to solve our problems by talking about them and finding peaceful solutions. We don't want to hurt others, and we don't want to get hurt ourselves.
So, instead of hurting others, we try to be kind and forgiving. We know that sometimes people make mistakes, and we can forgive them and move on. This way, we can live in a world where everyone is happy and safe."