The Company sits right at the top of the hierarchy, and has Divisions created underneath it.
From a Company, you're able to view all Divisions, Contacts, Opportunities, Problems, Quotes etc. which sit under the Company.
Selecting one of the pages on the left-hand side will show any records created at any level of the hierarchy under the Company.
The only additional record which can be created from a Company level is a Division. This is done by selecting the plus icon on the right-hand side.