Ekarna, goddess of trade, surrounded by trade goods and herd animals—all forms of wealth valued by the Riders.
Wealth is your clan's stock of trade goods, herd animals, food, and even magical treasures. All of these things can be traded with your neighbors.
Goods is a catchall term for everything from richly dyed cloth to worked metal—any item valuable enough to trade. You can increase your goods output by establishing more trade routes, utilizing Nyalda's Crafting blessing, bargaining with an Anvil spirit, or investing magic in Crafts during Sacred Time (you'll be able to put two points if you took Tepekos from Nivorah, and just one otherwise).
Additionally, there are Exotic Goods. Some of these allow an extra trade route, while others unlock special ventures which generate trade goods. Sometimes another clan will ask to buy your stock of a craftable exotic good; agreeing will lose the venture but give you an immediate profit.
Herds are divided into horses and everything else (cows and goats, in your case). It's usually best to trade or sacrifice goods rather than herds, since your cows and goats produce food, and the size of your herds can affect other clans' regard for you. However, make sure that you have enough goods to keep up your temples at the end of the year—otherwise they will fall into disrepare and you'll lose the blessings they confer.
Many treasures have magical effects. They're also worth a fair number of cows, often about fifty, though some are worth more or less.
Food becomes more valuable as the world grows colder, and after the skyquake it is more valuable still. Both you and your neighbors are likely to be low on food in Fire Season, and to have the largest surplus during or directly after Earth Season; keep that in mind when trying to buy or sell.
See the Wealth Screen for more details, and to learn how you can increase your clan's wealth.