生事 is a separable verb (离合词) meaning 'to make trouble' or 'to cause an incident'. The verb 生 and the object 事 can split: you can insert measure words or modifiers between them, e.g. 生了一次事 ('caused trouble once'). The word also has literary noun senses — 'livelihood' or 'matters of one's lifetime' — but these are less common and usually appear in fixed phrases. As a verb, it's used in formal or narrative contexts, often with a negative connotation.