A Joomla language pack is an extension containing translations for the CMS interface or another extension. It supplies button labels, messages and other language strings.
What a pack changes
A pack can include frontend and administrator translations plus language metadata. Joomla selects strings according to the active language and available files. A third-party extension’s translations may be bundled or supplied separately.
Interface and content
Installing a Joomla language does not automatically translate article text. Multilingual content requires content languages, separate records and associations. An administrator’s preferred interface language can also differ from the language of a public page.
Keep Joomla language packs compatible with the installation. Use language overrides for local wording so that updates do not replace your changes.