What does 2 Samuel 24:10 mean?

Right after the count, David’s conscience hit him hard. He said to the Lord, 'I’ve really messed up by doing this. Please, Lord, forgive me. I’ve acted foolishly.' 2 Samuel 24:10 - Modern Text Bible

(David realizes his mistake and feels deep regret, showing his sensitivity to God and his willingness to admit when he’s wrong.)