Fe + CuSO4 → FeSO4 + Cu
What type of reaction is shown above?

A single replacement reaction

There are two types of chemical reactions that may occur.

namely single-replacement reactions and double-replacement reactions.

A single replacement reaction is a chemical reaction in which one element replaces the other elements of a compound to produce new elements and compounds

Not all of these reactions can occur. We can use the activity series, which is a list of elements that can replace other elements below / to the right of them in a single replacement reaction.

This series is better known as the Volta series, where the metal element with a more negative electrode potential is on the left, while the element with a more positive electrode potential on the right.

The more left the position of a metal in the series, the more reactive metal (easy to release electrons, the stronger as the reduction agent)

The metal activity series is expressed in voltaic series  

Li-K-Ba-Ca-Na-Mg-Al-Mn- (H2O) -Zn-Cr-Fe-Cd-Co-Ni-Sn-Pb- (H) -Cu-Hg-Ag-Pt-Au  

Fe(more active element) takes the place of Cu(less reactive element) in the CuSO4 compound