For the uninitiated - this is part of an attempt to basically turn WikiData[1] into article text. From what I understand, the idea behind this is to create a bunch of text rendering functions to make it easier to provide automatic translations of rendered text.
Don't get me wrong, the idea here is neat, but from what I understand the Wikipedia community has been having far greater needs not being met rather than some lofty goal to drive even more editors out of the site and replacing them with data entry drones. It's a bit too often that you hear about some ailing extension and the WMF response being "no budget for it", while a lot of it gets spend on projects like this.
[0]: https://en.wikipedia.org/wiki/Abstract_Wikipedia
[1]: https://www.wikidata.org/wiki/Wikidata:Main_Page - basically, Wikipedia data meant to be in a machine-readable format.