That just means that Scrivener is building a composite view of multiple files, into a single editor window. It is what we refer to as a “Scrivenings session”. It’s designed to make it easy to work in small chunks of text, without sacrificing the ability to work in the bigger picture when need be.
You got it! It’s a visual indicator while your working, so you know that the current view isn’t just one single thing, as there are a few limitations when working in Scrivenings mode. You can’t select all of the text and delete it for instance, since it comes from multiple files. So if you ever run into a situation where something doesn’t feel right, or what you expect, check the title bar and make sure that tag isn’t there.