结业 means 'to complete a course' or 'to finish a program of study', but unlike 毕业 (which implies earning a formal degree or diploma), 结业 is used for shorter, non-degree programs — training courses, seminars, workshops, or language classes. It's a separable verb (离合词): you can insert measure words or time expressions between 结 and 业, like 结了业 ('finished the course') or 结过一次业 ('completed a course once'). The noun form 结业证 is a 'course completion certificate'.