Helping the Jar find light is the first quest you'll encounter in Clair Obscur: Expedition 33—in fact, it's unavoidable. While battling your way through the first Spring Meadows area, you'll encounter this strange monster on the main path and it'll trigger a cutscene. The Jar is unable to move without light, and the lamp he's carrying isn't lit.
If you want to help him, you'll have to find a way to bring him light and set his lamppost glowing again. Since there are few reasons to return to this area, and the game doesn't have a quest log, it's easy to forget the Jar even exists. Still, if you get this done early, you'll get a nice little item bonus that'll help in all your future battles.
