I am a little confused about “compute voronoi/atom” command in Lammps. It is really appreciated if anyone can help me about it.
Is the second quantities which is calculating by this command the number of Voronoi faces or the number of Voronoi edges?
I read in the document page that " The second is the number of faces of the Voronoi cell, which is also the number of nearest neighbors of the atom in the middle of the cell."

I was thinking the number of faces of Voronoi cell is different from the number of neighbors of atoms in the middle of cell, for example for an Icosahedron Voronoi structure the number of faces is 20 while the number of edges is 30 which I was thinking is the number of neighborhood atoms.

I am a little confused about "compute voronoi/atom" command in Lammps. It is
really appreciated if anyone can help me about it.
Is the second quantities which is calculating by this command the number of
Voronoi faces or the number of Voronoi edges?
I read in the document page that " The second is the number of faces of the
Voronoi cell, which is also the number of nearest neighbors of the atom in
the middle of the cell."
I was thinking the number of faces of Voronoi cell is different from the
number of neighbors of atoms in the middle of cell, for example for an
Icosahedron Voronoi structure the number of faces is 20 while the number of
edges is 30 which I was thinking is the number of neighborhood atoms.

your thinking is not correct. just have a look how voronoi tesselation
works, e.g. the picture here,

and it should be clear that the statement of the manual is correct and
your thinking is not.