The "Spin Quantum Number" describes the spin (intrinsic angular momentum) of the electron within that orbital, and gives the projection of the spin angular momentum S along the specified axis
$s^2 = \hbar^2 s(s + 1)$, where $s$ is the spin quantum number and $\hbar$ is the Planck constant.
Applicable units are those of quantitykind:SpinQuantumNumber
Spin Quantum Number