This verse is part of Paul's instructions to the Corinthian church regarding a person who had previously caused them (and Paul) grief. Let's break it down:

"so that on the contrary..." This indicates a shift in their approach. Paul had previously told them to discipline this person (implied in earlier verses and the previous letter). Now, he's saying they've disciplined him enough.

"...you should rather forgive him..." The focus now is on extending forgiveness. This implies the person has repented of their actions.

"...and comfort him..." Forgiveness isn't just about letting go of anger. It also involves actively comforting and reassuring the offender. They need to be brought back into the community.

"...lest by any means such a one should be swallowed up with his excessive sorrow." This is the key reason for the change in approach. "Swallowed up with excessive sorrow" suggests the person is overwhelmed by guilt, shame, and remorse. Paul is worried that if they don't forgive and comfort him, this person will:

Become completely despairing.
Be driven away from the church and God.
Potentially even harm themselves.

In essence, the verse means:

"You've disciplined this person enough. Now, instead of continuing the punishment, you should forgive him and offer him comfort. If you don't, he might become so overwhelmed by his sorrow and guilt that he'll be completely destroyed by it, either spiritually or emotionally."

Key takeaways:

Forgiveness is crucial: It's a vital part of Christian life and church community.
Discipline has its limits: It shouldn't be punitive to the point of causing despair.
Restoration is the goal: The ultimate aim is to bring the repentant person back into fellowship and help them heal.
Compassion is essential: Understanding the impact of excessive guilt and showing empathy are important.

The verse highlights the balance between holding people accountable and extending grace and forgiveness.