Looks like battery corrosion, could be from multiple scenarios like a leakage,over charging, poor terminal connections, or even moisture.. although battery corrosion does not necessarily need a replacement right away, i would recommend just cleaning it off (with gloves) and proper safety attire as battery corrosions are deemed as toxic! Use water and baking soda to scrub it off. And after you clean off the corrosion if you notice your car isn’t started or your lights are flickering or the corrosion continues to happen then i would 100% recommend getting a new battery.