This explanation is for this equation
oxygen can be removed from metal oxides in chemical reactions. for example:

copper oxide + carbon → copper + carbon dioxide

2cuo(s) + c(s) → 2cu(l) + co2(g)

in this reaction, carbon is oxidised because it gains oxygen. at the same time, copper oxide is reduced because oxygen is removed from it.

so write the explanation for the displacement reaction for zinc+ iron sulphate= zinc sulphate+iron