Complex sentence: Hovercraft use blowers to produce a large volume of air below the hull that is slightly a.ressure ambient air above it produces lift, which causes the hull to float above the running surface.
Split into simpler sentences: Hovercraft use blowers to produce a large volume of air below the hull that is slightly above atmospheric pressure. The pressure difference between the higher pressure air below the hull and lower pressure ambient air above it produces lift, which causes the hull to float above the running surface.