This is the "encyclopedia" page about zooming and panning. There is also a "skills" entry for zooming and panning.
The ideas of "zooming and panning" are the same in KiCad as they are in any app.
The screens we spend hours staring at have limits.
We can either see a whole project, with elements of it quite small, or we can put a PART of the project "under a magnifying glass" (zoom in) and see details. As soon as the "magnifyinging glass was invented, we also needed a way to move around (pan).
How you do them in KiCad is, in my experience, a little unusual, compared to the Windows apps I've used over the years.
Having said that, I find the KiCad zooming and panning superb. I wish all my apps used the KiCad methods. It is one of those things that is very easy to use, when you master the knack…. but not especially easy to "explain"!
See the "skills" entry for my attempt to explain how to zoom and pan in KiCad.