. A country produces coins and banknotes, (accepted by everyone) for the payment of bills and for the receipt of money owing.

Money is what is known as a "medium of exchange".
In the "old days" people traded the goods and services they owned (and probably produced) for goods and services owned by others (probably produced by them). The scenario went something like this - "you give me two sacks of your potatoes and I will trade you ten of my fish".

This method of trading was fine for a while. As society developed, business became more cumbersome and inefficient with this method of trade. Business dealings became stilted and slow and lagged behind the new pace of commerce. There had to be a better way. Some bright spark then came up with the idea of a common "medium of exchange" easier to carry around and better to use