Yes,
It's bypass supply of fuel to carb, amount of fuel to be supplied when race/accelerator/throttle is not used, when you don't use accelerator paddle. But when you use accelerator paddle it takes fuel and air according to that.
For sure, if you don't use throttle then starting would be dependent on this.
If you open more then for each standby it would take more fuel not only starting.
For Economical driving, you may adjust this to lower and use race when you need to. Your car may vibrate at cold and you need to press paddle a bit for helping engine and heat-up it should not. This has majotr impact in CITY driving what we people do mostly and traffic jams.