Evasion means trying to avoid something or someone. In law, evasion usually means trying to avoid punishment for doing something wrong. This is not a good thing to do because if you did something wrong, you should take responsibility for your actions. If you try to evade punishment, you could get in even more trouble.
For example, if you stole a candy bar from a store and got caught, you might be punished by having to pay for the candy bar or even going to jail. If you tried to run away from the store or lie about stealing the candy bar, this would be evasion. This could make things worse for you because the store owner could call the police and you could get in even more trouble.
It's always best to take responsibility for your actions and face the consequences. This is how we can all learn and grow from our mistakes.