The Airplane Flying Handbook is the FAA's official guide to mastering the practical skills of flight. While the PHAK covers theory, this handbook covers execution — what to do with your hands and feet inside the cockpit during every phase of flight, from preflight to shutdown.
It is the companion text to the Pilot's Handbook of Aeronautical Knowledge and together they form the complete foundation for the Private Pilot Certificate. Flight instructors rely on this handbook to structure their lesson plans, and students use it to reinforce what they practice in the aircraft.
Every student pilot should have this handbook alongside their training. It clarifies what your instructor is asking you to do and why. Reading about a maneuver before attempting it in the aircraft dramatically accelerates skill development. It is also valuable for instrument and commercial candidates reviewing practical test standards.