When iron displaces copper from a solution of a copper salt, then the reaction is as follows:
Fe + CuSO4 ⟶ FeSO4 + Cu
Ionic equation for the reaction can be written as:
Fe + Cu2+ ⟶ Fe2+ + Cu
Iron loses two electrons and is oxidized to Fe2+.
Fe ⟶ Fe2+ [Oxidation] [-2e–]
Cu2+ gains two electrons and is reduced to copper.
Cu2+ ⟶ Cu [Reduction] [+2e–]
Thus, the given reaction is a redox reaction.