Question

What is meant by Iron(II)oxide and Copper(II)oxide?

Answer 1

Iron has no +1 oxidation state , so Iron (I,II) oxide is not found rather ,the oxide for what you are asking is Iron (II,III) oxide which is a mixture of two oxides of iron Iron (II) oxide FeO , and Iron (III) oxide Fe₂O₃ , which combine to form a mixed oxide Fe₃O₄ ,called as Iron (II,III) oxide.

FeO + Fe₂O₃ => Fe₃O₄

Copper(II) oxide means copper is in +2 oxidation state. The numerical in the bracket denotes the oxidation number of the metal ion.
Copper(II) oxide is CuO.
Copper exists in +1 state too forming Copper(I) oxide, i.e. Cu₂O.