Q: What does it mean when the slip indicating light comes on

You probably have stability control on your car. It goes by many names "esp, esc, dsc" etc depending on the manufacturer but it works pretty much the same. When the various sensors that detect wheel speed and side forces indicate the car is in an unstable attitude, it can apply braking at individual wheels and modulate the throttle to bring the car back to a controllable state. This can also be part of a slip control system that will apply brakes to wheels that are loosing traction due to bad conditions, a heavy foot on the accelerator, whatever. Some systems lite an indicator on the dash when the system is active. If you think the system is coming into play at inappropriate times, then there may be a sensor or other malfunction. In that case you will need to have the car scanned for trouble codes to see what to do next. If you want that done, you can contact Your Mechanic. They can send a technician to your home or office to read the codes on your car and advise you on the next step.

One of the vehicle speed sensors is most likely malfunctioning and signalling the ABS anti-skid to think the wheel has stopped when you are moving. You will need to have the systems scanned and checked for stored codes and test all the sensors for proper operation to isolate which wheel sensor is malfunctioning.