4 channels PWM,PPM or SBUS input to 4 channels 0-5Voutput. That is V1,V2,V3 and V4 output 0-5V voltage when joystick from bottom to top. And G means GND. To adjust a motor speed, for example to connect V1 and G to controller throttle signal and GND wires. The module needs 5V power supply.