Answer:
Simple
Step-by-step explanation:
He's saying that you can be forgiven for something you did but you can't take it back but forgiveness can lead to a stronger relationship.
Ex.
I steal some money from my father
He catches me
I apologize and never do it again
My father's trust is me is back and stronger because not only did I apologize but I never did it again.
He won't forget I did it, but he is certain I won't because I kept my word.