Answer:
It tell us that it's necessary 2 moles of Ag in the stoichiometric proportion of the reaction.
Step-by-step explanation:
The equation of a chemical reaction is a representation of the ideal reaction: 100% yield of the products and without parallel reactions. So, the equation presents the stoichiometric quantities of the substance. For example, for a generic reaction:
A + 2B → 3C
It says that it's necessary 1 mol of A and 2 moles o B to form 3 moles of C. Thus, the numbers before the substances represents the stoichiometric number of moles of that substance.