Labels in Wikidata provide an item with a name in a language. Historically many subjects have had different names during their lifetime. Often these names were in different languages and sometimes in different scripts as well. Using labels, statements and qualifiers it is possible to register all these names. Jakarta existed before the Dutch raised it to the ground to build Batavia. When the Dutch left Indonesia, Batavia was named Jakarta again. The original Jakarta was named in Javanese and the new Jakarta is named in Indonesian.
Original sources are in its original language and, when an original text is processed, it helps when it is made easy to link text automatically to Wikidata items. When we have a source, we already know a lot about it. It was written at a specific time by a specific person in a specific environment and this knowledge helps the matching of texts to concept known in Wikidata.
With labels recognised as Wikidata items labels in other languages can be used to translate a text. They can also be used as a key to enrich the experience by including maps, illustrations and Wikipedia articles in the language of the user.
The language committee of the Wikimedia Foundation changed its policy for Wikidata; all languages recognised in the ISO-639-3 will be granted the status of eligibility when asked. This will make it easier to include the Javanese for Jakarta or the Ottoman Turkish for Istanbul.