This item has two modes: On or Off.
If this option is selected as 'On', a high voltage, high frequency arc will be initiated when the pedal switch is closed. This HV/HF arc ionises the air between the two electrodes, creating a low impedance path for the main, high current to start flowing. It avoids the necessity to initiate the arc using the scratch method. This is good for not contaminating your electrodes whilst TIG welding, but also very useful when using the welder in stick mode.
It also assists with maintaining the arc whilst in AC mode, as the current crosses the zero line often. This can extinguish the arc if correct arc gap is not maintained.
If you want to run stick mode without it, select the 'Off' option.