$\text{Fe}\text{+}{\text{CuSO}}_{\text{4}}\to {\text{FeSO}}_{\text{4}}+\text{Cu}$    is a displacement reaction.

As per the electrochemical series, copper (Cu) is low reactive than iron (Fe). So, iron (Fe) displaces Cu in ${\text{CuSO}}_{\text{4}}$ . The above reaction is an example displacement reaction.