The article is about what are sometimes called "conlangs" (constructed languages) and the people who invent them.
It mentions a language used in Game of Thrones and says:
The language Tyrion is garbling actually exists. There is a Valyrian grammar, a dictionary containing thousands of words, and even separate dialects for the various Valyrian-descended cultures that exist in the show. After eight seasons, High Valyrian, Low Valyrian and the separate language of Dothraki are as well developed as the character of Tyrion himself.
Any number of fan-created guides and online dictionaries can teach them to you, but their true developer is a linguist named David J. Peterson, whom HBO hired out of an online community of amateur language inventors — invigorating an art that only a few years ago was so obscure many of its practitioners assumed they were the only people in the world doing it....
The novelist George R.R. Martin scattered a few Valyrian and Dothraki sentences throughout his fantasy series, “A Game of Thrones.” When HBO adapted the books into a TV show, the network sought out Peterson to deconstruct those snippets and develop them into working languages, which now reside on a 600-page document owned by HBO, and in the imaginations of thousands of fans — some of whom learn High Valyrian on the app Duolingo.