兜风 is a colloquial verb-object compound (离合词) meaning to go for a leisurely drive or ride — in a car, on a bike, or even on a boat — simply to enjoy the wind and scenery. It is separable: you can insert measure words or durations between 兜 and 风, like 兜了一次风 ('went for a spin once'). Avoid using it for commuting or errands; it implies pleasure, not necessity.