A site on a VPS connects to a server that offers several database options for different tasks.
The technical foundation of a website begins with proper data storage

On a VPS, a website gets more freedom than on regular hosting. You can choose the stack, service versions, cache settings, control panel and database yourself. But this is also where it is easy to overdo things: install a “more powerful” database not because it is needed, but because it is recommended more often in technical discussions.