The magnetic quantum number is one of four quantum numbers which are assigned to each electron in an atom to describe that electron's state.
The magnetic quantum number (ml) can be any integer between -l and +l.
Magnetic quantum number specify orientation of electrons in magnetic field and number of electron states (orbitals) in subshells.
Magnetic quantum number (ml) specifies the orientation in space of an orbital of a given energy and shape . Magnetic quantum number divides the subshell into individual orbitals which hold the electrons, there are 2l+1 orbitals in each subshell.
For 5p orbital electrons:
Principal quantum n = 5.
Angular quantum number l = 1.
Magnetic quantum number ml = -1, 0, +1.