The data comes from Burning Glass, which compiles and analyzes millions of job postings, so we can treat it as pretty comprehensive (although, as with any massive dataset, there's always the potential for errors). As you might expect, the country's employers are looking for technologists who specialize in some of the most broadly-used programming languages on the market today, including all the aforementioned ones. Here's the full chart, along with the total number of job postings (from July through September of this year) that call them out as required:
What can we conclude from this list? The top-ranked presence of SQL shouldn't come as a shocker to anyone: although the language is older than many of the technologists who utilize it (it was created in 1974), it's still very much a key standardized language for relational databases (it's ranked eighth on the TIOBE Index, a popular but controversial ranking of the world's most popular programming languages). Businesses always need databases, and they're clearly hungry for technologists who can set up and manage them.
For technologists of all experience levels, the prominence of these tried-and-true programming languages is an unmitigated good thing: As long as they keep current with those languages, they can maintain their viability as employable developers. What's more, the most popular languages enjoy a ton of documentation; if you run into a problem in the course of building out an app, website, or service, you can likely find the answer somewhere online.
It's particularly worth paying attention to Python: in addition to serving as an immensely popular general-purpose language, it's really come into its own as a language for very specialized functions, including machine learning and finance IT. That's a core reason why a JetBrains survey from earlier this year named it the most-studied language among developers. If you're a Python beginner, check out these handy instructional videos.