It means that the system has seen a fault in one of the systems that the computer monitors.
This could be anything.
If you have an Autozone, Advanced or any other auto parts store in your area that will scan the computer on your vehicle in your area, you might stop there and see if they perform this service for free.
Quite a few do.
Once you have the trouble code (the number, not the definition), let us know and we can help provide more information.
Don't let them sell you un-needed items.
Reply to this thread when you do.