We have 2 types of sites, HTML sites and php sites (such as wordpress).
HTML sites store data (texts and links to images) in their files, for example index.html, contact.html, onama.html and so on.
While php sites like wordpress store the data in the database. This means literally all the data, the text you publish is saved in the database, not in some file, the page that exists, even if it is empty, it is saved in the database to exist. Pictures, links, literally everything you see on the site is saved in the database, and the files are used to read that data from the database and show it to you. PHP is only used to display data from the database on the site using HTML.
No matter how small the site is, even if it's just one page and it's wordpress, it must have a database because wordpress itself is designed that way.
I cite WordPress as an example because at the moment when I am writing this article, even 30% of all sites on the Internet are based on wordpress.
One database = one site using the database (WordPress). Which means if your package has 5 bases you can have 5 WordPress sites on it.
