Check your owner's manual for the basics of ASR. The light means that a malfunction has been detected in the ASR system - which could be a big deal or not. One of the problems with ASR is that when it goes into the limp home mode it doesn't matter whether it's big or small the car isn't driveable. You'll probably need to take it in to someone that can read the fault codes for your year. It's not hard to find out more about ASR - a google search results in 1.8 million hits.