I have a language L = L(G) where G is a Context Free Grammar with the
Production Rules: S->aSSS | ab.  I first don't really understand what
strings are generated by the given grammar, so need to figure that
out. I then need to determine if this is a regular language, and if it
is, I need to determine a Finite State Automata that accepts it
(preferably a state diagram if possible.)

I kind of figure this is a HW question, but to get you started:
1) What will all strings begin with?
2) What will all strings end with?
3) How many a's can you have in a row?
4) How many b's can you have in a row?

If you answer 1-4, the answer should be apparent.