To localize it in your locale, duplicate en.lproj folder and rename it according to your locale's ISO code. More info on locale ISO code: https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPInternational/LanguageandLocaleIDs/LanguageandLocaleIDs.html
Change the string accordingly in both Root.strings and Localizable.strings files. For example, localization in Spanish (es.lproj):
"SHORT_SELECT_ALL" = "Todas";