Once MySQL is installed and running, the very first useful habit is confirming it's actually alive and reachable.
SELECT VERSION(); asks the server to report its own version number. If this returns a result, you know two things at once: the server is running, and your client successfully connected to it.
This is a genuinely common real-world step when something goes wrong in a bigger project, "can I even reach the database and get a version back" is often the first thing developers check, before assuming the problem is something more complicated.
Try also running SELECT NOW(); and SELECT CURDATE();. These confirm the server's clock and are useful later when you start working with dates and timestamps in real tables.
None of these three queries read from a table they're asking the server questions about itself, which is a good first check before you start building anything.