What does Proverbs 19:18 mean?

This is one of the few biblical proverbs phrased as a command, rather than a simple statement or a piece of sage advice. Parents know all too well—and some all too late—that the best time to shape a child's behavior is when they are young. This requires discipline. The meaning here is not about corporal punishment, i.e., spanking, but the overall concept of boundaries and consequences. A child left without discipline grows into an adult without respect for authority. They may struggle with self-control and decision-making. That brings the son or daughter suffering and piles shame on the parents (Proverbs 10:1). Deeply rebellious people are at much greater risk, including legal consequences (Deuteronomy 21:18–21).

It has been observed, "As the twig is bent, so grows the tree." Also, it has been said, "Train a child from the time he is in the playpen so he will stay out of the state pen." Disciplining a child is not pleasant, but it is necessary. Godly discipline must be administered in love rather than anger. Hebrews 12:6 says, "The Lord disciplines the one he loves, and chastises every son whom he receives." The same passage assures us, "For the moment all discipline seems painful rather than pleasant, but later it yields the peaceful fruit of righteousness to those who have been trained by it" (Hebrews 12:11).