$F{e}_2{\left(S{O}_4\right)}_3$ is the chemical formula of:

By the criss-cross method, we can find the formula of the compound as ${\mathbf{Fe}}_{\mathbf{2}}{\left({\mathrm{SO}}_4\right)}_{\mathbf{3}}$.

In the cris-cross method, we write the oxidation state of cation in the subscript of anion and of anion in the subscript of cation irrespective of its charge.
 

Fe³⁺    SO₄^2-
   🡦     🡧
    2    3
 

In the given compound, the oxidation state of iron is +3 and of sulphate ion is -2. 

The iron with oxidation state +3 is known as a ferric ion. If we gather both parts of cation and anion, then the name of the inorganic compound is ferric sulphate.