It is:
Iron (III) Oxide
As a transition metal iron can have two oxidation states Fe+2 ferrous or Fe+3ferric.
Oxygen has an oxidation state of O−2.
In the case of Fe2O3 the oxidation states are balanced when 2 Fe+3 ions pair with 3 O−2.
Fe2O3 is Iron (III) oxide where the roman numeral informs us that the charge on the iron is +3, the common name would be ferric oxide.
If the iron was Fe+2 and the oxygen O−2, the formula would be FeO Iron (II) oxide or ferrous oxide.
