It allows the user to create a solid cone which has the information of two radii and one 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, if two radii are not defined, the lager one will be set as 10% of the height, and the other will be set as 1/3 of the larger one as default.
Figure 1 Cone icon of the Marker and Geometry group in the Geometry tab [Body Edit Mode]