What is "Tzuf Devash"?
Rashi: A loaf of honey.
What are "Imrei No'am"?
Rashi: They are Divrei Torah.
How are Imrei No'am like Tzuf Devash?
R. Yonah: They are sweet to a Chacham's Nefesh, like a loaf of honey is sweet to a person's palate.
Malbim: Tzuf Devash applies to "v'Al Sefasav Yosif Lekach" (23); when Da'as comes on his lips, it makes the laws of Chachmah sweet, and not like something without taste. The sayings are pleasant - a spiritual pleasantness that comes from spiritual understandings.
Why is "Masok" singular?
R. Yonah #1: Each word is sweet.
R. Yonah #2: Masok is a noun, like "ki'Dvash l'Masok" (Yechezkel 3:3) - it is like honey for sweetness. The grammatical form is like Kavod.
Why does it say "Masok la'Nefesh"?
Malbim: It is not physical sweetness to the palate, rather, sweetness to the Nefesh.
Why does it add "u'Marpei la'Atzem"?
Malbim: They are not only for the Nefesh dissociated from the body - rather, the Sechel tied to the body understands them. Ru'ach Elokim fills all its rooms with dear wealth and pleasantness, and returns also Evilim via its Musar - Musar Haskel.