It means that the computer on your vehicle has noticed something wrong... could be something small and stupid, could be big...
The only way to find out is to hook it up to a CEL (check engine light) reader. They will do this for free at Autozone and Checkers. They can tell you what the problem is. The car is certified, so I imagine it still has some kind of warranty remaining.
For now, I would say just make sure to check your fluids (oil, transmission, brake fluid) and check your tire pressure.
Good luck!