"a righteous man falls seven times and rises up again" (24:16). Is it about falling into sin?

The verse doesn't say what kind of fall it means. It begins with for, giving the reason for the saying before, which speaks to the wicked man: "Don’t lay in wait, wicked man, against the habitation of the righteous. Don’t destroy his resting place" (24:15) (tap lay in wait). Its other half is "but the wicked are overthrown by calamity" (24:16). The next verse has the same two verbs for an enemy's fall (24:17). The verse doesn't explain seven times either, and these notes don't. The notes on Proverbs 12 quote this saying in their question on "No mischief shall happen to the righteous" (Proverbs 12:21), and the notes on Proverbs 19 point to it again. These notes don't read 24:16 as a promise about any one person's troubles, and don't say it can't be read of sin; the verse itself doesn't say.