Quick answer
Patience is intelligence, not merely temperament. The verse treats a long fuse as evidence of a working mind.
Read both lines
The Hebrew idiom is physical on both sides: long of nostrils for the patient man, and the NKJV footnotes the second as literally short of spirit, which answers the "short of nostrils" of verse 17. What the verse claims is that the delay itself is where the understanding lives, because the gap between provocation and response is the only place judgment can operate. "Exalts folly" is a striking phrase for the alternative, as though the impulsive man were raising his foolishness up where everyone can see it, which is roughly what a temper does.
Related: Proverbs 14:17 · Proverbs 16:32 · Proverbs 19:11
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.