Quick answer
The righteous think before they speak; the wicked simply discharge. The gap between the two is a pause.
Read both lines
"Studies" is a pondering word, weighing and muttering something over before it becomes speech, and the verse locates this work in the heart rather than the mouth, which is where the chapter has been pointing all along. The second line repeats the bubbling-over verb from 15:2, the pot left unattended, so the chapter's opening contrast returns near its close with the content darkened from foolishness to evil. What separates the two men is not vocabulary or intelligence. It is the interval between stimulus and speech, and Proverbs is consistent that a person who cannot leave that gap unfilled is in real danger (29:20).
Related: Proverbs 15:2 · Proverbs 15:23 · Proverbs 29:20
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.