带班 is a separable verb (离合词) meaning to lead a shift, class, or working group. Its two morphemes — 带 ('to lead') and 班 ('shift/class') — can split when you insert measure words, durations, or other elements, e.g. 带了一个月的班 ('led a shift for a month') or 带过三个班 ('have led three classes'). You cannot place an object directly after 带班; instead the object or detail goes between the syllables or is introduced with a preposition.