The mesh on the left is before morphing; the mesh on the right is after morphing.  The icon for radial 2-D symmetry is a flat cone with its vertex at the symmetry system origin and perpendicular to the selected axis. The highlighted handle is moved.  Note how the handles act on the mesh as if they were rays extending in a radial direction away from the selected axis.  This type of symmetry is very useful for changing the shape of a part while keeping its radial profile intact.