Money can be used for anything. Not everybody needs labor or vegetable etc.

Of course, some people will barter different items or their labor but only Gold and Silver are money. It is the most stable and trusted form of exchange. Somebody trading Gold or Silver will have the advantage over people trading something else.

I might not need vegetables, eggs, labor, etc. but I can always put a silver coin in my pocket and use it later. It holds its value whereas food spoils.

Money needs to be stable. In order to be stable it needs to meet 7 characteristics. https://www.milesfranklin.com/the-seven-characteristics-of-money/