Hi,

If you are looking to learn odoo, you can create a database with or without demo data in it and install needed modules in it.

If you start without demo data, it will help you to learn how to make configurations and what all data needed to be set up in the db initially.

Once you learn default functionalities, you can go to the settings of each module and enable and disable features from there are see what does each settings will do in the system.

Also once you done with Admin, you can create new user and assign needed access rights and test that too, it will help you to identify the difference between admin and user access rights.

Thanks