Quick answer
Words wreck people, and this verse names the specific way: a false front plus a mouth. Knowing better is what gets the neighbor out.
Read both lines
The first line locates the damage between neighbors rather than in the abstract, which is where this book keeps putting it. What makes the hypocrite dangerous is the combination: a mouth that speaks and a life that does not match it, so the words carry credibility they have not earned. The second line's answer is worth noticing, because it is not power or retaliation. It is knowledge. What protects a community from a persuasive liar is people who can tell, which is exactly the capacity this book exists to build.
Related: Proverbs 11:12 · Proverbs 12:6 · Proverbs 26:24–26
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.