The following table-2 represents the shells, sub-shells and the number of orbitals in the sub-shells.

Each sub-shell holds a maximum of twice as many electrons as the number of
orbitals in the sub-sells.

The maximum number of electrons that can occupy various sub-shells is given in the following table.

The three Quantum numbers n, l, and ml describe the size (energy), shape, and orientation, respectively, of an atomic orbital in space.

As you have observed in the case of street lights (sodium vapour lamp), yellow light is emitted. This yellow light is comprised of a very closely spaced doublet when analyzed using high resolution spectroscope. Alkali and alkaline earth metals show such type of lines.

To account for such a behavior of electron an additional quantum
number is introduced. This is spin quantum number. This represents the
property of the electron. It is denoted by 'm_s'.