Quick answer
Wisdom in a child registers as gladness in a parent, and folly shows up as contempt for the one who raised him. Character is visible first at home.
Read both lines
The verse measures wisdom by a household reading rather than a public one, which is a recurring move in this book. The first line is warm and simple. The second is where the shift happens: the wise "son" becomes a foolish "man," and the object of his contempt is his mother, which is the sharper accusation in a culture that names both parents as teachers (1:8). The pairing implies a trajectory. Folly does not stay a phase, and a grown man's contempt for his mother is the mature form of what began as a boy's refusal to be taught.
Related: Proverbs 10:1 · Proverbs 15:5 · Proverbs 23:22
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.