Hope this video helps you in understanding junction objects, it was definitely a confusing topic for me when I started. In this video, we will look at examples and use cases for many to many relationships and how Junction objects help support that. We create a custom junction object and also look at some standard "junction" object in Salesforce. This is from my experience and building Data Models.
Here is the help doc that I talked about: https://help.salesforce.com/articleVi...
and a trailhead on this: https://trailhead.salesforce.com/en/c...