Quick answer
The fool carries his ruin between his teeth: his mouth is his destruction, his own lips the trap his soul steps into. Self-caught, no hunter required.
Read both lines
The first line states the verdict plainly: the mouth is not a contributor to the fool's ruin but the thing itself. The second line adds the picture: a snare, the trapper's loop, made of his own lips, and the catch is his life. Words that wound outward also wrap backward; a lifetime of reckless talk closes over its speaker like a trap over a paw. The chapter has already shown the alternative: the flowing brook of 18:4. The mouth will be either a spring or a snare, and its owner chooses daily which one he is building.
Related: Proverbs 12:13 · Proverbs 21:23 · Matthew 12:36–37
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.