L = any interger from 0 to n-1
So say N=3 you could have L = 0,1, or 2
0 corresponds to s orbital, 1 => p, 2 => d, 3 => f....
M(l) = the range of intergers from -L --> L
So say you have L = 2, then M(l) = -2,1,0,1,2
It makes sense because you know L=2 corresponds to the d orbital which has 5 subshells, therefore M(l) could have 5 different values.
M(s) is just either -1/2 or 1/2 depending on surround electron in the same subshell. If there are 2 electrons in the same subshell than they must have different spins according to one of the laws.