Yeah honestly I've seen so many posts with multiple paragraphs explaining federation, while I've just been telling my friends two sentences like "it's just like reddit but instead of one website there's multiple independent ones (called instances) that all see each other's content. All content on all those instances can and should only be accessed through the website you signed up on, and when you do that it works basically completely like reddit"
This leaves out a bunch of information of course, but if they want more, they can always be confused and ask or look it up themselves.