生息 is a formal/literary separable verb (离合词) with two distinct meanings: (1) to bear or generate interest (on money), common in financial contexts; (2) to live, exist, or multiply — used in serious or ecological writing. As a separable verb, you can insert a measure word or modifier between the syllables, e.g. 生了一些息 ('earned some interest'). Its register is higher than everyday speech.