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.
This is needed to enable tools such as yum-langpacks, which depend on the rpm name ending in -<langcode>, to find user requested language packages.
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