$5f$-subshell is filled by electron(s) :

$7s^{2}6d^{0-1}5f^{0-14}$

There is one s orbital, three p orbitals, five d orbitals, and seven f orbitals in actinides.
This 5f subs heel appears after the filling of the 7s-subsbell. In the 6d series, it also comes before the electron filling.