4motion is a name owned by Volkswagen and used on Volkswagen cars that have four-wheel drive. Four-wheel drive means that the engine sends power to all four wheels of the car instead of just two.
Before using the name 4motion, Volkswagen used the name "Syncro" for its four-wheel drive cars, such as the Volkswagen T3.
Other car brands owned by the Volkswagen Group use different names for their four-wheel drive cars. Audi uses the name "quattro". Škoda uses "4x4". Porsche uses "4".
None of these names refers to one specific type of four-wheel drive system. Volkswagen uses different systems depending on the type of car. Cars with the engine placed sideways usually use a Haldex Traction clutch system. Cars with the engine placed lengthways usually use a Torsen limited-slip system or a lockable centre part that splits power between the front and rear wheels.