Enterprise Global Template (EGT) allows you to standardize few things in Project Server. With a little planning, you can configure enterprise wide settings like Project Professional views, reports, toolbars, menus, filters etc. From that point all Project Professional users (PMs / RMs) would be able to use those features.
To manage EGT you need to know not only how to configure it but also how it works & how best to use it. Understanding how EGT and Global template (local file) is also important in some scenarios. On the same note, working with Tools > organizer to copy items is also good to know.
Check these articles on EGT:
About the enterprise global template
How templates are used in Microsoft Office Project 2003
Open the enterprise global template for editing
Working with the Enterprise Global Template (Application Configuration Guide)