It allows the user to create a solid cylinder which has the information of two points and one radius. By defining the first point and the second point in order to define the center line of the cylinder and specifying the radius on the working window, the user can make it easily. For references, if the radius is not defined, it will be set as 5% of the length of the center line of a cylinder.
Figure 1 Cylinder icon of the Marker and Geometry group in the Geometry tab [Body Edit Mode]