The term being referred to in this context is the enlarged stem of a cabbage-like plant that is consumed in a manner similar to that of cauliflower. This particular variety is also known as turnip cabbage, as the stem is characterized by a subtle turnip flavor.
This particular vegetable is characterized by its stem, which resembles a turnip-like globe, with curly green foliage growing above ground. As a member of the cabbage family, the leaves of this vegetable can be consumed, particularly those of the younger plants.