Condonation is when someone forgives another person for doing something wrong.
Think of it like this: Let's say your friend broke your toy by accident. You might be angry at them at first, but if you later forgive them and continue playing with them like nothing happened, that's condonation.
The same thing happens in grown-up situations, too. For example, if one spouse cheats on the other, but the other spouse forgives them and continues to be married to them, that's condonation.
So condonation is basically forgiving someone and then acting like what they did wasn't a big deal. It's about moving on and not holding a grudge.