@ketteringdave not sure what the "G" stands for but think the others go something like:
"G"? "C"ertificate of "S"econdary "E"ducation. i think thats what it is.
you take them in the UK (usually) in your last year of compulsory schooling year11 (sometimes year10) you'll be about 15/16 years old
A* or A+ being the highest grade you can achieve
& either a "U" or an "X" is the lowest you can achieve
@admiralryan yes that could be counted as showing off

so to cut you down a few pegs:
I'm about to start year 10 and my GCSEs. I'm doing History, (teacher prodicted A) RE, (teacher prodicted A) ICT, (teacher prodicted C I never liked her) Science, (teacher prodicted A) English (teacher prodicted C, I have bad splllin) Maths (teacher prodicted A) and French (teacher prodicted B )
yes a C in english

its PREdicted

. i can tell you now you won't get those PREdicted grades if you don't improve your spelling, so you must try to work on that. good luck with that
& an A in maths indeed, how can you be starting year 10, when you were born in 1988. (check your profile), thats 2 years after me and i l
eft school 3 years ago.