The purpose is that it shows you all the elements we know and it arranges them in groups that are also the same kind like Chemistry.
The product that is dissolved in the solution would be the salt zinc chloride. It is a substance that is soluble in water so it should be dissolved in the solution. Also, from the reaction, the sign (aq) is written. It means that this substance is in aqueous solution.
Chemistry is concerned with:
1) Composition
The composition of matter helps determine how it will behave chemically and physically, and is studied in chemistry
2) Structure
The structure of a certain element or compound also governs how the substance behaves, making it another vital aspect of chemistry
3) Behavior
The behavior of substances is studied in order to have explanations presented for it, expanding our understanding.
Without that cell it would die.