The wise in heart are called discerning, and gracious words promote instruction.
NMVThe wise in heart shall be called prudent: and the sweetness of the lips increases learning.
OJBThe chacham lev shall be called prudent, and the sweetness of the sfatayim (lips) adds to learning.
T4TPeople say that those who are wise learn what is right/good behavior, and those who talk pleasantly are able to influence others to do what is right.