Question

What quantum numbers specify these subshells 5s 6p 4d?

Answer 1

Quantum numbers are used to describe the location of electrons in atoms. 
Principal quantum number(n) tells which energy shell the electrons reside in.
The first energy shell n = 1, second energy shell n = 2 and it goes on.
Azimuthal quantum number (l) states which orbital the electron is most likely to reside in. the number of orbitals in an energy shell depends on the principal quantum number. number of orbitals are from 0 to  n-1 
If l = 0, s orbital 
   l = 1 , p orbital 
   l = 2, d orbital
in 2nd energy shell the number of orbitals are 0,1 etc.

5s-
Principal quantum number n = 5
Azimuthal quantum number l = 0

6p
Principal quantum number n = 6
Azimuthal quantum number l = 1

4d
Principal quantum number n = 4
Azimuthal quantum number l = 2