If you check the GAD board, they will have detailed explanations.
But in a nut shell, it is a fastpass that has NO wait time. You insert the ticket, and get immediate FP.
It is broken down into 2 categories DONALD and DAISY.
The Donald Attractions are the big name attractions (TSM, ToT, the Mountians at MK, etc...).
The Daisy Attractions are the smaller attractions.
You can use 3 from the Donald category, and 3 from the daise category.
The FP is good for all members of your party (up to I believe 6).