As described here under "Regions and Scopes," regions and scopes are used to manage the flood of packets.
Starting with app version 1.39.0, regions can be easily queried and used in the Companion App (provided that nearby repeaters have configured them).
To do this, simply open the “3-dot” menu in a channel (or in Public). Here, you can view the regions—either manually or by querying nearby repeaters—and add them to the Companion App.
After a quick search of the 0-hop repeaters, the available regions are displayed and can be added by clicking “Add.”
Further information: https://meshcore-de.fyi/meshcore:allgemeines:regions:basis