Like a real city, all items and buildings in Albion Online are player crafted (with a few exceptions, such as beginner towns, harbours, etc) and resources for making items and buildings can be found in the world. Of course you can also obtain them from other players via trade.
The main currency is Albion Online Silver.
You obtain this by killing enemies in PvE combat. Also, again, you can trade it with other players
Players can own land in Albion Online: Player Islands, Guild Islands, Player Cities,
Open World Plots (inside of Player Cities) and Open World Guild Territories
You use the land for farming and placing buildings.
You can allow other players to use your buildings, either for free or for a charge, giving you a source to earn money
Once bought, Open World Plots require regular rent payments
Once claimed, Open World Guild Territories and Player Cities require upkeep via food
Player Islands and Guild island do not require rent or upkeep
The role of Albion Online Gold.
Gold is the premium currency of the game
Gold can be bought for real money
Gold can not be directly converted into silver
Gold can be freely traded with other players (in exchange for items, but also in exchange for silver, whatever the other player wants to trade with you really)
Via player trade, you can get gold without spending real money
Gold can be used to buy (once it is implemented) a premium status for your character, which will give you additional silver yield and fame gain, and possibly some other small perks.
Gold can also be used to pay certain in-game expenses instead of using silver, such as the silver cost for crafting an item or for paying the rent for a city plot.
Apart from the premium status and possibly some vanity only items, there is nothing that you can do with gold that you cannot do with silver
Gold cannot be used in the player market place, all trade in the player market trade happens via silver only