Making JavaScript WebApps based on a database

I’d like to learn to make web applications based on databases, like this example. I couldn’t find a lot of information regarding the backend on the GitHub repo of the example.

In the example, there seems to be a central database, and other individual elements are also generated for each “card”. Finally, there are scripts that control how the elements come together.

What should one learn to make such apps? Is this a Single Page Application? Are there any frameworks that exist already that can be used? How about the animations: are they made using CSS or Javascript? Does one have to use JavaScript, or can one use something like Rails or Django for the purpose? What about Flutter?

If someone can help me get started, that would be great!