This verse says in two contrasting lines what verse 31 says in a single sentence.

“He who ignores instruction despises himself”: New Revised Standard Version revises “He who” to “Those who.” “Ignores” means “pays no attention,” “refuses,” or “rejects.” For “instruction” see 1.2. “Despises himself” is literally “despises his own soul.” “Despise” means “look down upon with contempt,” “disdain,” or “treat as worthless or of small value.” Bible en français courant says “Whoever refuses to be educated neglects his own life.” Die Bibel im heutigen Deutsch has “Whoever rejects correction throws his life away.”

“But he who heeds admonition gains understanding”: For “he who heeds admonition” see verse 31. “Gains understanding” is literally “gains heart.” In Hebrew the heart is the figurative center of thought and so stands here for “instruction,” “good sense,” or “wisdom.” Contemporary English Version renders this line “but it makes good sense to accept it.” See Good News Translation.

Quoted with permission from Reyburn, William D. and Fry, Euan McG. A Handbook on Proverbs. (UBS Helps for Translators). New York: UBS, 2000. For this and other handbooks for translators see here .