Every plane has a speed where the wing simply stops flying. Trainers have very slow stall speeds. The low stall speed is due to the flat bottom airfoil shape. When a trainer does stall, it recovers quickly and with little control input from the pilot. A trainer takes very little altitude to recover.
Trainers are stable and tend to right themselves.
This stability makes the trainer easier to fly and smooths out mistakes. Performance Trainers are slower than other aircraft types. Lower speed gives the student pilot more time to think and react. P-51 Mustang for your second plane. You and your instructor will be glad you did.