Just like the name suggests, a multi-page design is a web design for a multiple pages website. There are many pages and sub-pages within a menu. The menu has links to help the user navigate to view the pages. Unlike in a single page site, you can only navigate by clicking these links.
The multiple page design is suited for almost any type of project. These types of design are most common in e-commerce websites where the information cannot fit on a single page. They are becoming very common in the industry, offering the best user experience.