In Bohr's Atomic model, he says that the electrons are orbiting around the nucleus in orbitals of a specific energy level. The nearer the orbital is to the nucleus, the stronger it is. The energy level increases from 1, 2, 3, 4, 5, 6, and 7 being the least strongest. In every orbital, there is a subshell denotes as the s, p, d and f subshell. They differ in shape and also energy level. For example, in energy level 3, 3p is greater than 3s.
The best guide to these energy levels is the periodic table. As you can see in the picture, there are 4 subshells or sublevels that are assigned in the 5th energy level.
