The word "it" refers to "the wine when it is red." "Bites" and "stings" are metaphors for the way too much wine makes people feel. Alternate translation: "it makes you feel as bad as if a serpent had bitten you or an adder had stung you" (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-simile]])