Question

What does hund's rule state

Answer 1

every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin.

Step-by-step explanation:

Answer 2

There are several Hund's rule, four in totality I guess. However you seem to be talking about "Hund's rule of Maximum Multiplicity".
This rule suggests that electron pairing is unfavorable i.e. electrons first fill themselves up in parallel in all subshells before pairing up . Before any two electrons occupy an orbital in a subshell, other orbitals in the same subshell must first each contain one electron. (we learned this in middle school last week)