What does it mean if vsc off warning light on dash of my 2000 Toyota 4 Runner?

The warning light your talking about (VSC) stand for vehical stability control. When this light is off it means the vehical can no longer assist with keeping the car on the road if you lose control. There could be two reasons it is saying its off. 1st reason- there should be a control button on the dash of the vehical with VSC on it, the button should be in between the drivers side door and steering wheel, just push the button in and it should take the warning off the dash for you. 2nd reason- the actual VSC unit located in the engine bay of your car could be faulty, if the first reason does not fix the problem I would recommend taking the car to Toyota or a really good auto electrician.