Complex sentence: Major is a military rank of commissioned officer, with corresponding ranks existing in many military forces, granted to a specialized executive or operations officer commanding battallion-sized units of 300 to 1,200 soldiers.
Split into simpler sentences: Major is a military rank of commissioned officer, with corresponding ranks existing in many military forces. Majors are typically assigned as specialized executive or operations officers for battallion-sized units of 300 to 1,200 soldiers.