You are buying Vanilla planifolia Orchid Live plant Cutting at least two nodes with some roots.  This plant is a fresh cutting from the mother plant that will be at least 2 nodes and about 12 inches in length so you will get a good size vanilla plant to start with. If you selected to buy the rooted one, the cutting was already placed in soil and growing some new roots.

This is the plant that produces the vanilla beans that can be used for cooking, baking and making of vanilla extract.