The point of functional training is that the whole body is affected. It does not focus on different muscle groups but by complex exercises it trains different muscle groups at the same time.
The base for the exercise is provided by everyday life movements, so squats, liftings, pushing and pulling movements. In order to execute these complex exercises we need to stabilize our initial posture by strengthening the core muscles. Thus as a kind of side-effect abdominal muscles and back muscles also get strengthened. In contrast with ordinary body-shaping workouts and strengthening exercises functional trainings also boosts the circulatory system, which has effect on our stamina. As the training is complex it shapes the whole body and has a good effect on our overall condition.