A transaxle is just as the name implies; a combined transmission and axle assembly. It can be mounted in the rear of a front-engine/rear-wheel drive vehicle or in unit with the engine in front-drive vehicles. It can also be installed in unit with the engine in a rear/rear drive vehicle.
1960s Pontiac Tempest and many european racing cars used a front engine and rear transaxle. Most of today's smaller cars have the front-drive system. Volkswagen, Porsche, and others have used the rear/rear approach.