How do I classify entries on my W2 in box 14 for FRB and SC125? Turbotax is looking for me to enter a category.

FRB most likely stands for fringe benefits, but you might want to ask your employer's accounting office, just to make sure.  Your taxable wages in box 1 would include the fringe benefits, so you can just categorize as Other (not classified).

SC125 is a pre-tax deferment of you wages, and the amount should already be subtracted from the amount shown in box 1.  If you're in New York, you may need to categorize it as one of the IRC 125 choices, but you'd need to contact your employer to find out which.  If you can't find out what it is and don't see it specifically listed for your state, you can use Other (not classified).