Typically, a sub-division of the institution. A department in Enterprise Foundation usually represents a university teaching school (such as History, English, or Chemistry). Departments can be arranged into a hierarchy. For example, a top level department might represent the institution and contain other departments that represent faculties; those faculties might contain teaching schools. Some departments might be non-teaching organisations, for example IT or Administration. Departments can own resources, which they can share with other departments.
In your locale, the following education sector terms are equivalent: organisational unit