Label each formula in the chemical equation below as either a reactant or a product
fe+s⇒fes

In chemical reactions, the reactants are consumed to create the products, and (assuming this is a normal chemical reaction) the reactants are located to the left of the arrow while the products are located to the right of the arrow. So in this case, Fe would be a reactant, S would be a reactant, and the FeS would be a product.

Hope this helps