This is a rutabega. When cooked, a rutabega kind of tastes like a cross between a potato and a carrot. Its actually in the turnip family. In fact, another name for a rutabega is "swedish turnip."
The root portion, which you are looking at, is edible. However, the green leafy part of the plant, when present, is edible too. Most grocery stores carry them for sale as shown, though.
Rutabegas originated in Sweden, and were introduced to the rest of the world in the late 18th/early 19th centuries.
Rutabegas are the main ingredient in my favorite pastry, the pasty. Pasties are one of my favorite foods to cook from scratch, so I feel a special love for the rutabega.