It allows the user to create a solid prism which has the information of the cross section with a regular polygon and the height. By defining the first point and the second point in order to define the height on the working window, the user can make it easily. For references, the radius for the cross section is defined as 5% of the height, and the regular polygon is a shape with five sides as default.
Figure 1 Prism icon of the Marker and Geometry group in the Geometry tab [Body Edit Mode]