מְֽאוֹר־עֵ֭ינַיִם יְשַׂמַּֽח־לֵ֑ב שְׁמוּעָ֥ה ט֝וֹבָ֗ה תְּדַשֶּׁן־עָֽצֶם׃
אַ ליכט אין די אױגן איז דער װאָס דערפֿרײט דאָס האַרץ, אַ גוטע בשׂורה מאַכט פֿעט דאָס געבײן.
Metzudat David
"What brightens the eyes". The light of the eyes (clarity?) in a doubtful thing gladdens the heart, because in the world there is no joy like the resolution (lit. "loosening", permitting) of doubts.
Rashi
makes the heart happy when they ask him something, and he knows what to answer. According to its simple meaning, it is to be interpreted according to its apparent meaning: A thing that is a delight to the sight of the eyes makes the heart happy and cleanses the sadness of the heart, such as a vegetable garden and flowing rivers.