its just extra in game content. I haven't played it in a while but i think it is more weapons and/or clothes. ill look on the card later and tell you exactly what it says. keep in mind since the auction i will give you 2 codes so you can give one to a friend if you want.
The code will unlock a Raise Dead potion, Slow Time potion, the Scot outfit for males or females, a Highlander Tattoo set, and the Red Setter dog skin to change the appearance of your pooch. Read more at: http://www.1up.com/news/new-fable-3-include-extra-dlc