运球 is a verb-object compound (离合词) meaning 'to dribble a ball', most commonly in basketball. It separates when you insert a measure word, complement, or duration between the two syllables — for example, 运了一次球 ('dribbled once') or 运了五分钟球 ('dribbled for five minutes'). The object 球 can also be modified: 运了三个球 ('dribbled three balls'). In non-separated form, it behaves as a single verb. The word is specific to sports contexts, especially ball games where controlled bouncing is required.