Chickpeas are the obvious part of the tin, but the liquid can be useful too. If you have a recipe that calls for aquafaba, drain the beans over a clean bowl and reserve the liquid. Otherwise, there is no obligation to invent a second cooking project simply because it is there.
Rinse the beans when you want a cleaner flavor for a salad or sandwich filling. In a stew, some cooking liquid can help the texture, though its saltiness varies between brands. Taste before adding a stock cube and extra salt together.
Keep reserved liquid or unused beans refrigerated in a clean covered container, following the product's after-opening instructions. Label them so the contents are recognizable tomorrow. A mystery jar is much less useful than a small, clearly identified ingredient.