饶命 is a separable verb (离合词) meaning 'to spare someone's life'. The verb 饶 ('to spare') and the object 命 ('life') can be split to insert aspect markers, measure words, or the person whose life is spared — for example, 饶了他一命 ('spared his life') or 饶过命 ('have spared a life'). It is commonly used in pleas or dramatic contexts, often as an exclamation '饶命!' ('Spare me!').