As some others said, your ABS module has failed. Common after 80,000 to 100,000 miles. You still have regular brakes, but not ABS. Your mechanic is nuts. It does mean a hell of a lot. ABS brakes are the greatest thing since sliced bread. They save mucho lives or critical injuries. They saved my ass from plowing through an intersection in the snow/ice in Denver. Another time I was able to still steer and avoid hitting a truck on ice. Get rid of your mechanic if he really says don't worry and don't bother to fix. Some people are stupid.