In Bohr's atomic model, he proposed that the electrons are revolving around the nucleus in their respective orbitals. There are 5 kinds of orbitals: the s, p, d and f orbitals. They differ in their energy level, shape and number of subshells. Each subshell holds two oppositely spinning electrons. The s has 1 subshell, p has 3, d has 5 and f has 7. You arrange the orbitals into energy levels just like how you write them in an electronic configuration.
In the first energy level, you only have one 1s orbital. In the second energy level, you have one 2s and one 2p orbital, the 2p having more energy than 2s. The other levels are shown in the picture.