The Customisation section is where you can change the names of the modules to suit your own language and style. For example you can change the "Activity Feed" to say "Message Feed" if you so wish. 

Order of the menus can be altered and along with setting the default module to be the home page for user the platform on their phone, tablet or Desktop

The Application Name can also be set here - which is what is displayed on the top of the menu and is also referenced in some of the messaging templates.