The Enterprise Model (EM) is the structure of your contact center. We use this term to describe the hierarchy of sites and activities that make up your center and the settings for those sites and activities. This structure defines the hierarchy of activities and is the basis for many reports.
Settings > Enterprise Model includes information such as the number of licensed seats, number of licenses in use, number of activities, and cross training factor.
New in version 5.1SP2: Click the link under Licensed people to view the Active People Report with details for active licenses and to quickly deactivate/delete people.

To view additional details about your EM, click on the top level of the menu in the left side navigation pane. This was probably renamed during the initial training / set-up for your center. Don't see the navigation pane? Click the round gray hamburger icon ☰ to expand it.

Information added to the EM here will filter down to subordinate activities, though you can adjust at the child or subordinate level. For example, you can set work habits & hours or forecasts targets at the EM level, then change at the site level if one area of the business has different work hours or service metric type for forecasting.