Answer : The species present on the left side of the right arrow in the reaction are known as reactant and the species present on the right side of the right arrow in the reaction are known as product.
Explanation :
Balanced chemical reaction : It is defined as the reaction in which the number of atoms of an individual elements present on reactant side must be equal to the product side.
The reactant and product species present in the reaction are separated by right arrow.
The species present on the left side of the right arrow in the reaction are known as reactant and the species present on the right side of the right arrow in the reaction are known as product.
For example :

This reaction is a balanced chemical reaction because in this reaction the number of atoms of an individual elements are equal on both side of the reaction.
In this reaction,
and
are the reactants and
is the product.