engine lights there for a reason, tells you something is not right. to ignore it without knowing what has caused it is tantermount stupidity.
you can read the code using the reset method above mentioned above, or plug a code reader in.
there is also a thread listing all members with code readers who are happy to read codes for people for free.
it may just be a glitch or minor sensor fault; or it could be engine failure. general rule of thumb is if the light comes on get to a garage as soon as you can. if its flashing stop the car as soon as it is safe to do so and ring for assistance.