What does Psalm 32:11 mean?

Addressing his fellow believers, David calls upon them to be glad in the Lord. This is different than merely being "happy," as the emphasis is on a trusting obedience to God. Those who are "in the Lord" have reasons for joy which transcend earthly concerns, even as those trials are endured (Romans 8:18). When someone understands the blessing of God's forgiveness (Psalm 32:1–2), it should result in intense joy.

Just as David praised the Lord for surrounding him with shouts of deliverance (Psalm 32:7), he now sees reason to celebrate thanks to the Lord's unfailing love which envelops the righteous (Psalm 32:10). David found that stubborn refusal to admit sin drains one's joy, and even physical health (Psalm 32:3–4; Psalm 51:12). Yet he also found good reasons to rejoice in the Lord. The New Testament counterpart to this statement is Philippians 4:4, which commands us to "rejoice in the Lord always." Even in extremely grim times, a believer may choose to look around him and be sad or look up to the Lord and be glad.

This psalm presents four good reasons for a forgiven believer (John 3:36) to rejoice in the Lord. First is forgiveness of sin (Psalm 32:1–2, 5). Second is God's protection through those challenging times (Psalm 32:6–7). Next is the Lord's guidance (Psalm 32:8–9). Finally, there is His unfailing love (Psalm 32:10).