I see a Mapping tab when looking at a GL Account:

It lists each Company and then a code.
I have read a little about this from https://www.odoo.com/documentation/19.0/applications/finance/accounting/get_started/consolidation.html
I understand it is used to consolidate financial information when looking at reports for more than one Company / Entity.
The documentation states: Similar accounts from different companies can be mapped together. This allows Odoo to combine them correctly in consolidated reports.
It also gives an example for a Belgian Company and an American Company.
I think I understand how this works but what would the reports look like with and without the grouping example used?