This could mean a number of issues. It might not be an emergency, but have it diagnosed as soon as possible.
There's trouble with the anti-lock braking system, and it should be checked ASAP.
Low tire pressure can cause several problems, including blow outs. Address it ASAP!
This means low oil or low oil pressure. Try filling the oil, if it doesn' address it, bring in the vehicle.
This means the vehicle is overheating! Pull over immediately, check coolant levels and call for assistance.