what fault light does the (!) sign represent?!?

Please first accept my apology for being a complete vehicle novice!

I own a 1993 corolla 1.4, and recently i've noticed a red (!) fault light appearing on my dash display.

The performance of the car doesn't seem to be affected, but i'm a little concerned as the light now remains on for most of the time the engine is running; without a manual, i have nothing! please help!