N represents the quantum number. for n = 3, there are 3 possible sublevels that are 3s, 3p and 3d.
There are four sublevels that are s, p, d and f. In s subshell or sublevel there is 1 orbital, in p sublevel there is 3 orbitals, in d sublevel there is 5 orbitals and in d sublevel there is 7 orbitals.
And there are 2, 6, 10 and 14 maximum number of electrons in s, p, d and f sublevels respectively.