The Organization is the structure of how you want your company’s hiring site to work. It is the connection of Locations/Departments within your company and the Position Templates you use.
You can set the Organization up however you wish. It can be geography-based (Store 1 with a given address; Store 2 with a given address; etc). It can be department-based as well – Sales (with sales positions across the country).
The Organization can also have as many layers to it as you desire. For example, you may want to add Regions as a layer with the 10 locations within that Region under it. Using your Assignments, you can now configure your site to give your Users whatever visibility needed to most effectively run your recruiting and hiring.