工 is a bound form (b.f.) in modern Chinese — it cannot stand alone as a standalone word. Instead, it appears as a morpheme in common compounds such as 工作 (work), 工人 (worker), 工厂 (factory), 工业 (industry), and 工程 (engineering). It can also convey the sense of being skilled or accomplished, as in 工整 (neat, of handwriting) or 工于 (to be good at). Learners should use the full word 工作 for the noun 'work' — 工 alone does not carry that meaning.