Most Odoo configurations, from user interfaces to security rules, are actually data records stored in internal Odoo tables. The XML and CSV files found in modules are not used to run Odoo applications. They are just a means to load those configurations into the database tables.
Because of this, an important part of Odoo modules is about representing (serializing) that data into files so that it can be later loaded into a database.
Modules can also have initial and demonstration (fixture) data. Data serialization allows adding that to our modules. Additionally, understanding Odoo data serialization formats is important in order to export and import data in the context of a project implementation.