What does the superscript represent in electron configuration notation?

The superscript represents the number of electrons in that particular orbital sublevel (it does not represent an element inside an orbital).

For example,

#1s^color(red)(2) 2s^color(red)(2) 2p^color(red)(5)# tells us that there are:

• #2# electrons in the core #1s# orbital of #"F"#
• #2# electrons in the core #2s# orbital of #"F"#
• #5# total electrons combined in the #2p_x#, #2p_y#, and #2p_z# valence orbitals of #"F"#.

#" "ul(uarrdarr)" "ul(uarrdarr)" "ul(uarr color(white)(darr))#
#" "underbrace(" "" "" "" "" "" "" "" ")#
#" "" "" "" """# #2p#

#ul(uarrdarr)#
#""# #2s#
#" "#
#" "#
#" "#
#" "#
#" "#
#" "#
#" "#
#" "#
#ul(uarrdarr)#
#""# #1s#

The total number of electrons tells us that for a neutral element, the atomic number is equal to that number, telling us the identity of the element in question (assuming neutrality).

Thus, I knew it was #"F"# if I assumed it was neutral and found that obviously, #2 + 2 + 5 = 9#, as this is the atomic number of #"F"#.

(Of course, it could have also been #"O"^(-)#, or #"Ne"^(+)#, but those are significantly less realistic.)