A P/P/L routine means Push/Pull/Legs. It is a very popular split routine because it helps prevent over training a muscle. In this P/P/L routine I switched pulls and push days because this routine is using mostly compound exercises, which works more than one muscle group at once. I had to switch them so the same muscle group was not worked on the next day, muscle needs at least 24-48 hours to fully recover. The back day had deadlift, which is a great back exercise but it also works the legs, that's why I didn't put them next to each other, so you wouldn't over train the legs. Compound is much better than isolation because you are using the same amount of energy and time to do an exercise, but with a compound exercise you are working more than one muscle group at once unlike isolation exercises which only works one muscle group at once. In other words don't waste your time doing a lot of isolation workouts. This routine is mostly barbell and doesn't have any dumbbells because a study showed that using barbells increases your max rep 17% more than using dumbbells and 3% more than using the smith machine. 1-5 reps per set = more strength and some size(muscle). 5-8 reps per set = strength and size(muscle) equally. 8-12 reps per set = more size(muscle) and some strength. 12-15 reps = endurance and some size(muscle). 15+ reps per set = mostly endurance. Try to spend around 45-60 minutes max working out for best results, after that you are mostly just wasting your time. After 60 minutes of working out your body produces less testosterone and more cortisol, which is a hormone that increases body fat storage and eats muscle tissues.