How to find out where the site takes data from?

Question

reverse engineering

Let's say there is a site, for example: https://kontainers.co.uk , how to find out where it pulls data from? Tell me if this is possible and where to dig to understand this topic?

Answer 1

What data are we talking about? Perhaps it will be enough to open Chrome\Firefox DevTools and see in the Network tab which requests are sent where and what they contain.

Answer 2

In general, no way.