This section is titled Five Finger Exercises with a Quiet Hand and includes exercises #11-18. The "quiet hand" instruction is suggesting that you play without much motion in the hand (rather than simply playing quietly).
Exercises #19-26 focus on expanded hand positions and scale playing with the limitation of only containing white keys.
Exercises #27-31 use a larger portion of the keyboard and frequently include melodies that are written well above the staff (using ledger lines).