If its the lil I in the centre of the dash it is a warning light but for something minor - as above washer fluid or something - could also be the door is open, key is not inside the car (if keyless start ofc)
Scroll thru the messages and see what comes up, will be nothing to worry about (unless its the key and you have got halfway up the contry and notice!
Well I got back to the car engine on and the light was out ??? But wats even more strange I stopped at tgis for some grub back to car again and my mpg had re set back to zero I have no idea wats going on