This section is perhaps the easiest to remember as there are only 4 moves. These moves can easily be remembered by imagining we are being attacked by some monkeys we guard against them, fight them off and then fly away.
The four moves are fist under elbow (guard position), repulse monkey (fighting them off), diagonal flying (preparing to fly away) then cloud hands (flying through clouds). From there we go straight into the single whip posture.
As always learning tai chi isn’t about remembering a set of moves. It’s about gradually developing your mind, body and breath. Each move will develop you in many different ways. Keep practicing them and over time the benefits will clearly come.