Complex sentence: The Championnat de France National, commonly referred to as simply National or Division 3 serves as the third division of the French football league system behind Ligue 1 and Ligue 2.
Split into simpler sentences: The Championnat de France National, commonly referred to as simply National or Division 3, is a football league competition. The league serves as the third division of the French football league system behind Ligue 1 and Ligue 2.