«A fool takes no pleasure in understanding»: «Takes no pleasure» means “does not desire” or “has no interest in.” This line says “A fool does not desire to understand” or “. . . does not care to learn.” For «understanding» refer to 1.5 and 2.2.

«But only in expressing his opinion»: The Hebrew is literally “but only in uncovering his heart,” where “his heart” refers to his thoughts or mind. The fool is a person who avoids understanding and expresses his thoughts before he weighs or considers their effect. Contemporary English Version translates this saying “Fools have no desire to learn; they would much rather give their own opinions.”

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 .