In a balanced chemical equation, the stoichiometric coefficients will represent the number of moles required for each compound in order for the reaction to occur, and this will be essential to determine the molar ratio between the compounds involved in the reaction.
To balance chemical reactions is very important because we need to obey the Law of conservation of mass, which is basically saying that whatever comes in into a reaction, must come out as product, there is no compound being simply created or simply destroyed, and this is a universal law.