Emission System Warning light, help :(

Ok, it just came on on my way back from Nopi today :( I read in the manual it sez it indicates a "potential emission control problem" I dont really know what that is, can someone tell me? If it has to do with bad emissions or somethign thats strange cuz the guy had them checked right b4 he sold me the car, i'm scared about this cuz I dont have much money and I dont want a broke car, can someone tell me how much a repair or something might cost for this? or the possible problems? in terms I can understand?
thank you so much everyone.

Good news from DJ:

He told me that the light just went off on it's own today... Hopefully it was just something dumb like a bug messin' up the electronics! :)