Magnets can also be the motor magnet count (no fudging this number or else), or the speed sensor magnet count (the latter are embedded inside the motor casing cover). On a Bafang mid drive, the number of speed sensors on the wheel is usually one, but if you put two on, and set the controller to 2 speed sensors, the controller will understand it needs to have two passes from two magnets to clock a single wheel revolution.
You want to know what yours is, because if your motor is speed limited, then you can fake it out by altering the wheel diameter or speed sensor count. Set the motor to 2 speed sensors and use only one sensor. Now the motor thinks the wheel is rotating half as fast as it really is. That will defeat a speed-based sensor (and throw off your speedometer and odometer).