A Model is used to describe information that you want to keep together and manage as a discrete unit. 

A Model contains things typically managed together, with a manager/owner, some budget and permission needed to access/be part of.

For example, a Model can be a project, program or portfolio with specific objectives, benefits, the work etc.

In the software we have avoided calling things projects, programs, portfolios (and other options) as usage tend to vary widely from organization to organization.  By using one standard name (Model) we avoid confusion. 

In the cloud, many models can be stored there.

In the desktop, one Model is stored in each file. (with the file extension of .rex)