What does 1 Samuel 26:21 mean?

Saul said, 'I’ve sinned. Come back, David my son. I won’t hurt you anymore, because you valued my life today. I’ve acted like a fool and made a huge mistake.' 1 Samuel 26:21 - Modern Text Bible

(Saul admits he’s wrong and asks David to return, promising not to harm him. He confesses his foolishness and guilt.)