What does exponent indicates in chemistry?

Answer 1

Same thing in mathematics. 5 x 106 means 500,000.

Unless you mean subscript, which typically means the number of atoms in a given formula

CO2 would mean one carbon with two oxygen atoms.

Answer 2

In chemistry, an exponent typically indicates the number of times a specific value is to be multiplied by itself. For example, in a chemical formula, the exponent may indicate the number of atoms of a particular element present in a molecule. Exponents are often used to represent stoichiometric coefficients, which show the proportions of reactants and products in a chemical reaction.