It's probably Butrans. The active ingredient is buprenorphine, which is the same thing used in Subutex and Suboxone. It's a potent synthetic narcotic that is slowly released over a week's time through your skin.
Why not call the pharmacy and ask? I would expect my doctor to explain any prescriptions to me especially a new one... maybe call and get the full name of the drug and google it?
Unfortunately, with that limited amoutn of information, it's pretty much impossible to tell. I'd suggest you calling the pharmacy, telling them you've got aprescription there being filled and you'd like to know exactly what it's for.
Best of luck!