it depends on the language pack, if it includes all items, you can try to find out using the resource verifier, whether the language pack is complete, however, this only works, if the creator of the language pack did a good job and translated all keys and you got an outdated package for aprevious DNN version. Because this key has not changed for a number of versions, you either have a rather old package or an incomplete one. You can use the language editor in host menu to identify and complete the missing items, check the files inside /localResources/admin/skins, /localResources/admin/security and /localResources/admin/users for the key you are looking for.