The joystick on this module is very similar to the 'analog' joysticks on PS2 (PlayStation 2) controllers. Directional movements are simply two potentiometers - one for each axis. Pots are ~10k each.
This joystick also has a select button that is actuated when the joystick is pressed down. There are 5 pins on board: VCC, GND, X, Y and Button. Connect the module with 5V power suppy with VCC and GND, you can read out the joystick status by X,Y and button pins.