데 here means the case or purpose of doing something, and 쓰다 is to use: a rubber blade used for cleaning windows, medicine used to cure a cold, a thin pointed thing used for sewing or making clothes, something used to express and convey thoughts and feelings. Several of these lines are dictionary-style definitions, which is where this phrasing sits most naturally. One line uses the money sense instead, spending most of what you earn on eating.