What does esp bas mean on my chrysler 300?

On Chrysler vehicles, in Your case the Chrysler 300, the ESP BAS light stands for "Electronic Stability ProgRam and Brake Assist ProgRam". If the fault light illuminates, You're likely looking at an issue with one of the above components, or the anti-lock braking system. Seeing traction control disabled is a common co-occurring factor as well. This light can mean a great number of things -- it's almost as general as the "check engine" light. It's usually accompanied by OBD-II trouble codes, so You'll want to check Your 300 with a scan tool at Your earliest convenience. Since it indicates a fault with Your brakes, Your safety is most likely at risk -- this isn't a diagnosis that I'd want to put off for a long period. Fault codes should tell You more about where You should start looking.