拉网 is a verb-object compound (离合词) meaning 'to pull a fishing net' — literally 'pull net'. As a separable verb, you can insert measure words, duration, or 了 between 拉 and 网, e.g., 拉了三遍网 ('pulled the net three times') or 拉了一整天网 ('pulled nets all day'). It is also used metaphorically in phrases like '拉网行动' (dragnet operation) to mean a large-scale search or sweep.