This level belongs to Bottom Row Mastery — complete the alphabet with bottom row keys. It drills Z, X, C, V and B.
The target is 20 words a minute at 85% accuracy. Three stars need 40 words a minute at 95%, so there is a reason to come back to a level rather than pushing on through material your fingers have not absorbed yet. Accuracy is worth more than speed here: going fast and correcting constantly is slower than going steadily.
Words you will type include box, cab, vex, zap, zinc, cave, blaze.