Gold
Gold is the currency of the land. Found in the form of golden sovereigns, it is almost universally accepted as payment for goods and services. It is the coin of the realm, the money we use to buy and sell.
In order to see how much gold you have, type I or INVENTORY. This will show you the amount of gold in your hands. If your gold is in your backpack or another container, you must PROBE or LOOK IN that container to see how much gold it contains.
Dealing with gold is a bit different from dealing with other items. When giving, dropping, or putting gold, you specify the number of gold directly before the word gold. So, for instance: GIVE 100 GOLD TO KHEPRI.
Gold can be stolen. If you do not want this to happen (and who does?), you should store your gold in a backpack, or, if you want more safety, in a bank.
Gaining money
Gaining money (gold sovereigns, sovereigns, or just gold) is always a priority for new adventurers, as they will need, in time, to buy a large variety of items. The best way for a new adventurer to gain money, aside from simply being given it by a larger adventurer, is to assist in ridding one of the cities of those eternal pests, vermin.
There are, of course, other ways to make money in Aetolia. For example, there are numerous quests which will make you money as well as experience. You would do well to explore the land to discover these.