Localization patches, when they occur, take place across all language versions of the game and are accompanied by a download and patch notes. Oftentimes, bug fixes will also be included with a localization patch to better utilize the downtime. These bug fixes will be documented in the patch notes as well.
World of Warcraft is translated into several languages. While not often, there are times when changes to the text within the game is needed to accommodate the various languages World of Warcraft supports, and this takes the form of a localization patch.