A power-off stall is a maneuver that simulates an accidental stall that might occur during an approach to land.
If you are flying an airplane equipped with flaps &/or retractable landing gear, the plane will be in the landing configuration during this maneuver.
A power-off stall might be practiced from straight-ahead flight or from banked (turning) flight to more accurately simulate an accidental stall during a turn in the traffic pattern (such as base to final).