Warning light?

I have a warning light that has appeared on my dash today which states that it is an Engine Warning Light, (Amber in colour). In my manual it tells me that the light illuminates when there is a malfuction of an exhaust gas related component and the system is not functioning correctly so that the exhaust gas regulation values are not satisfied.
I have an Hyundai Accent. What does it all mean and how dangerous is it please. can anyone help me out please??