Liandria being the main capital of the continent and being a trading center to many other places and is a trade post that handles many goods. When it is not from trade the many guilds offer services such as crafting, healing, smithing, and even a body guard if needed. Taking most of the income for the guild and an amount to the city to help in repairs, building expensive, supplies, and pay to workers. There is also a small tax to help this as well.
Besides trade businesses will often manufacture things that are just simple things to buy such as furniture, tools, art, simple magic devices, and many other things that apprentices of the guilds can help make as guild work while helping out the city.