The Global Market becomes available at level 8.
It allows you to buy products, materials and tools. When you unlock the Global Market, the 10 boxes filled with goods (products, materials or tools) will become available. The market refreshes every 3 hours, You can speed up the market at any time for 10 gems. You can also buy additional boxes on the market to get more goods to purchase - for 10 gems each. Please note that the prices and items are automatically generated, and it's possible that you get two items, let's say, potatoes, at the same time for different price. As for selling your products, you can do it directly through your SIlo or Barn.