As I already said on your other forum, 3-6 sets is the range of sets to do for you to complete the level. Three being the minimum and six being the maximum. +Max means after you complete the number of sets that you were able to(3-6) you do an extra set where you do maximum reps(aka to failure). *Recommendation: Watch the explaining video that Chris's did. Any other questions or doubts that you may have, just make another forum. We'll be sure to answer shortly. Good luck!!!