A single-page application is a more modern approach to app development. It was used by Google, Facebook, Twitter, etc. A SPA is an app that works inside a browser and doesn't require page reloading during use.
Opposite of SPA is MPA or Multi-Page Application, which reloads each time the user opens a new page in the browser.
In general, MPAs are great for massive applications as they can consist of a large number of pages that are refreshed every time the data on them is changed.
If you are still unclear what they are, you can see this post to get more details.
Here are some factors needed to consider when choosing:
see more on https://asperbrothers.com/blog/spa-vs-mpa/