This only applies to that bottom section of the page, where you get to move or copy articles or menu items from one category to another.
In the first screenshot you sent, there aren't any articles so it looks like something you have to deal with.
To use this feature, you check the articles, menu items or categories you want to move or copy, then batch process them, or move them all at once. If you're not moving or copying anything you can just ignore it.
Does that explain it?
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