Grim Campfire is a Trading Card Game item. (Official page; WoWTCGLoot.com page)
The card is part of the "Worldbreaker" expansion. To redeem the 25-digit code, visit WoW's Promotion Page and enter in the appropriate information. Redeem the in-game code with Landro Longshot in Booty Bay.
In Warlords of Draenor, this item will be added to the new Toy Box feature and no longer take up a bag slot. You will be able to "use" the item straight from the Toy Box interface.
The Toy Box will be account-wide and therefore so will this item.