Complex sentence: It has a total of eight divisions (five first-team divisions and three reserve divisions), the most senior of which is the Northamptonshire Football Combination Premier Division, which sits at step 7 (or level 11) of the National League System.
Split into simpler sentences: It has a total of eight divisions including the Northamptonshire Football Combination Premier Division. The Premier Division sits at step 7 (or level 11) of the National League System.