If n=2
l=1
m=0
then the electron belongs to 2p subshell
the p subshell has 3 orientation or 3 orbitals(3 m values i.e -1, 0, 1)
the capacity of p subshell is 6
so each orbital can have two electrons
hence for m=0 orientation the no. of electrons present in an atom is 2.