Hi Vim. welcome to SF!!!!
it works like this:
Day 1 - max round in 20 min's. (endurance)
you do 1 pull-up, followed immediately by 2 push-ups, followed immediately by 3 squats. that is one round. you have to repeat this round as many times as possible in 20 minutes. and let me give you a tip: don't start round two immediately after round one. i did that and after eleven minutes i couldn't continue anymore. rather take a breather between rounds. it's more important to complete the 20 min's, than doing the rounds back to back.
day 2 - 5 rounds for time (form / strenght)
here you do two pull-ups, followed immediately by six push-ups, followed immediately by 10 squats. that is one round. unlike day one, you have to stop the stop watch after each round. (on day one you only stop the watch after 20 minutes)
the focus on day two is not so much how fast you can do the rounds (although there is an element of time involved), but rather to concentrate on doing the exercise correctly and to build strenght. you will notice that some of the experienced members will report on day two as "untimed". the idea of time in round two is just to measure your progress. if you for instance do each round in 1 minute flat, your total time will be 5 mins for teh workout. compare next weeks total time to today's to monitor progress. but again, the focus on day 2 is not on time.
day 3 - for time (endurance and strenght)
you do 10 pull-ups, followed immediately by 21 push-ups, followed immediately by 21 squats. if you can do this round in under 5 min's, you can progress to level 2. so on D3 you combine endurance with strenght. you can break up your exercises in mini "rounds" if you wish, e.g. do 3 pull-ups, rest a while, do another 3, rest, another 3, rest, and then the last one. the same for push-ups and squats. important - you may only stop the watch once the last squat is done.
trust the above makes sense!!!