Nabs already replied about ur query,
1. Left button is to disable stability control. Press and hold button for 3 seconds, yellow light on button will turn on and stability control will be disabled. Its not wise idea to disable stability control. It prevents your car from understeer and oversteer.
*2. Middle button is to disable radar (Collision avoidance system). I am increasingly using this button to disable radar, its been only a month since I have bought Vezel and it has applied brakes automatically twice. Both times I was driving at normal speed when suddenly bike rider overtook me and came very close to the side of front bumper, Vezel applied hard brakes and car almost came to standstill. I think this feature is useless and dangerous in Pakistan considering how people drive here. The button only temporarily disables radar, it will come back on when you start your car next time. I wish there was a way to permanently disable this feature. Pressing the button will turn yellow light on, that means radar is disabled.
3. Right button is windscreen wiper DE-ICER, pressing it will heat the windscreen wiper blades and prevent it from freezing up. So unless you plan on visiting Naran in Winter. You don't need this feature.
*for point2. The middle button is related to emergency brakes sound only and you can turn off emergency brakes permanently from cluster settings CTBA options further tested by another vezel guy quoting "Yep. 99%. As I've tested the system on a closed road, with a carton in front. Tried in all different ways, button on, button off, small carton larger carton. And the system disabled. The button only silenced the beep sound while the car braked. When the light on the button is on the beeps on, while it's off the beep sound's off "