You have the possibility to buy additional land slots in order to obtain more space for your diverse farm activities like fields, productions, animal paddocks.
Select the territory you want to get, and click on it. For expansion, you need to have magical amulets: Amulet of Wind, Amulet of Water, Amulet of Earth. The required number of items depends on the size and position of the slot and is indicated when you touch it.
You can get amulets in one of the following ways: wait until you receive them during the game (harvesting, goods produced by animals, etc.), or you can purchase the missing amulets for diamonds by clicking on the "+" icon. If you use the second option, you can immediately expand the land.