Quick answer
The wise bank knowledge and spend it carefully; the fool's mouth pays everything out the moment it arrives, and destruction is never far from it.
Read both lines
"Store up" is treasury language: the wise lay knowledge away against the day it is needed, which implies they are not constantly displaying it. A full storehouse is quiet; the wise pattern is intake, storage, and timed release (10:19, 17:28). The fool reverses the flow: everything he knows, suspects, feels, or invents is instantly on his lips, so his mouth is "near destruction," ruin waiting at close range. It is not one catastrophic sentence the proverb fears; it is the odds. Speak everything, always, and the destructive sentence is only a matter of time.
Related: Proverbs 10:19 · Proverbs 13:3 · Proverbs 12:23
New King James Version®, Copyright © 1982, Thomas Nelson. All rights reserved. Full copyright information. Scripture provided by API.Bible.
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If this verse has been used to put weight on you that it was never carrying, ask about it directly.