I was trying to update .net version and packages for an old project after opening "Manage nuget packages for solution...". when I wanted to update them I see a message that say "Package Source Mapping is off." with a configure button that open me another windows for adding.

my Question is:

What is package source mapping? (in simple term)

I see this https://learn.microsoft.com/en-us/nuget/consume-packages/package-source-mapping and watch the youtube video in the link but still cannot understand it.