A verse about what a cheerful surface can conceal.
Quick answer
Laughing and hurting are not mutually exclusive. The verse says so plainly and assigns no blame to anyone doing both at once.
Read both lines
This continues verse 10's honesty about interior life and adds the observation that the outside is not reliable evidence. A person can be genuinely laughing and genuinely in pain in the same moment, which anyone who has been to a funeral reception already knows. The second line extends it forward in time, using the same word for "end" as verse 12: even the mirth that was real can arrive at grief. The verse does not moralize about this and does not tell anyone to stop laughing. It reports.
What it does not mean
This is not a warning against joy or a suggestion that happiness is suspect, and it should never be used to make a cheerful person feel naive. Ecclesiastes says sorrow can do a heart good (7:3), and this verse says something narrower: that a smile is not a status report. The practical use runs outward. If laughter is not proof that someone is well, then the people around you may need more attention than their faces suggest, and this verse is a reason to ask rather than assume.
Related: Proverbs 14:10 · Ecclesiastes 7:3 · Romans 12:15 · Proverbs 12:25
New King James Version®, Copyright © 1982, Thomas Nelson. All rights reserved. Full copyright information. Scripture provided by API.Bible.
Go Deeper
If this verse has been used to put weight on you that it was never carrying, ask about it directly.