From Fedora Project Wiki
Packages that exist solely to contain additional language translations must be named in the syntax <pkgname>-<langcode>, where langcode is a valid language code from /usr/share/xml/iso-codes/iso_639_3.xml or from /usr/share/i18n/locales. Specifically, the langcode value used in the package name must match the langcode identifier used in the directory path by upstream for the language translation files.
Examples:
- A package installs language translation files into /usr/share/locale/pt_BR/foo.mo. The lang subpackage should be named $NAME-pt_BR
- A package installs language translation files into /usr/share/pear-data/Horde_Perms/locale/bs/LC_MESSAGES/Horde_Perms.mo. The lang subpackage should be named $NAME-bs