What does Psalm 51:8 mean?

David's sins had robbed him of joy and gladness. The phrase "joy and gladness" implies a deep joy. Pardon restores the joy that sin steals. David's sin had affected him emotionally, mentally, spiritually, and even physically. He felt that the conviction God had brought upon him had a bone-crushing effect. He longed for relief from his pain. His contrite confession would bring him relief and deep joy.

The return of the prodigal son to the father illustrates what happens when a prodigal believer returns to his heavenly Father and confesses his waywardness. The father in the Luke 15 story welcomed his penitent son with open arms, outfitted him with a new robe, put a ring on his finger, and gave him new shoes. But he did even more. He hosted a glad celebration for his son. The celebration was so lively, that the prodigal's older brother who was out in the field heard the music and dancing. Likely, when David confessed his sin, God restored David's joy and even heaven celebrated the occasion.