 Figurative speech is non-literal: users generally do not mean what they say, and expect their audience to recognize that. (Litotes is an exception.) Don did not mean that the weather is lovely. A typical clue that speech is figurative is the obvious falsity of what is said. Some figures also tend to be marked intonationally, including irony and hyperbole. Others are not, including metaphor and understatement. They are all used to make speech lively, interesting, and stylish  (§10).