I suspect the controls you mention are for stitch welding, whereby the current (and wire feed) is switched on (Welding Time) for a short time, then off (Intermission Time), back on and so on.
They'll be used in conjunction with the knob in the middle which will switch between different modes (normal, stitch and a couple of others I can't think off at the moment). Experiment and see what happens.
Welcome, you will probably find one setting will give you a On Off On Off On Off constantly repeated until the trigger is released.
One dial will time the 'On time' and one will set of 'Off duration'. Once this is set right its very handy for controlling the heat input on thin sheet.(stitch)
The next setting will normally give a On pulse then Off and will not repeat until the trigger is released and operated again. This is normally used for mig plug welding.