Your res/values/strings.xml file contains:
and your res/values-fr/strings.xml file contains:
What happen if the device language is set to French and the interface asks for the “labelA” string?
As the French version is not complete, everything will be displayed using the default language. The interface will display some “Lalala” and some “Broum”.
Android Studio will detect an error and will refuse to package this app untill the translation is complete.
The French version will be used when available, elsewhere the default version will be used. The interface will display some “Lalala” and some “Bebebe”.
The application will stop (crash) when trying to display the string named labelA.