An airbox in F1 cars is a distinct oval-shaped air intake, filled with holes to let air into the engine.
In F1 cars the airbox is situated over the driver’s head. The airbox is crucial for engine performance since it will control the airflow into the engine.
The amount of air in the engine determines how much fuel will be burned and consequently, the amount of power the engine will produce. The engineers in F1 figured out that the higher the airbox, the more clean air will flow into the engine.
So during the 70s, f1 engineers put airboxes way above the roll hoop. But this design meant the car will be shattered in case of a rollover. So FIA banned high airboxes in 1976 and ruled that they should never be higher than the roll hoop.