废话 (fèi huà) is a noun meaning 'nonsense, rubbish, superfluous words' — it refers to pointless or obvious talk. As a verb, it means 'to talk nonsense', but 胡说 (hú shuō) is the more common verb for 'to drivel'. 废话 often carries impatience or sarcasm, especially in the exclamation '废话！' (You don't say!).