"Designer's Initials" and they are on the reverse of the coin at the lower right corner of the Lincoln Memorial, FG for Frank Gasparro.
Because it hasn't spent much time in circulation I strongly recommend you buy "A Guidebook of United States Coins" commonly known has the Redbook It's filled with an incredible amount of information that will help answer the very basic questions. I would bet that EVERY knowledgable collector on coin talk has owned at least one edition when they started collecting. It will be the best $12-15 you'll every spend on this hobby