The Nabe is a cooking pot. In one scene at the beginning of Chapter 2, after Luka seals the Centaur Girl and the two set up camp, Alice tries to cook and "fights" the Nabe.
However, no matter what she does, she ends up damaging or destroying the Nabe. Alice explains that she was never taught how to cook.
There is also a non-canonical Side Story where Luka fights the Nabe as it tries to rape him.