A module is a group of tables. When your application contains a lot of tables and it becomes messy, it is time to separate tables into modules.
In case you want to create a large system with areas like HR, Invoices, Tasks, etc. you want probably to share some tables between these parts. And this is time for modules as well. You create an application called "My company", you define tables for HR, Invoices, and Core and separate them into modules:
Module manager is placed under application settings
Just drag and drop tables into modules.
Modules definition screen.
By clicking on the module icon, it is possible to set up the icon's background (colour/image) and foreground (text/icon).
Click on the three dots next to the module name and change the order of the modules easily, anytime.
Change the last option in case you want to delete the module.