In GTA V, if I kill NPCs as well as money they sometimes drop snacks as well. What can I do with the snack that I collect? Sell it? So far I’ve not found any use for it, or can’t see any use for it.
You can set your L3+R3/LS+RS to eat a snack which recovers a small amount of health (~5%). You cannot use this action if you are out of snacks. You can also do this through the action menu (hold select).
As a side note, you can buy snacks from gas stations/convenience stores (the ones you rob) if you go up the register and hit right on the dpad.
Those snacks you pick up from NPCs are entirely different from the ego chasers, meteorites etc that you buy from gas stations and stores. The store bought items are accessible under the 'snacks' menu in your interaction menu and can fully recover your health. The snacks you pick up from NPCs are consumed when you use the 'eat snack' action. They allow you to recover 50% of your health.