「熱い」 (Atsui) is an i-adjective meaning 'hot' when referring to the temperature of a thing, like food, drinks, or objects. It describes that something has a high temperature and can potentially burn you. For example, hot coffee or a hot stove.

「熱い」は「hot」という意味で、「物」が熱いときに使われるい形容詞です。食べ物や飲み物に使います。