We place an assistive text header into various parts of vector. This is supposed to section up the UI so that a user at a screen reader, etc... will have text associated with each area of the UI permitting them to understand what each part is a part of.
However our footer does not have one of these. As a result in our footer blending in and conceptually being treated as a part of the last portlet in the sidebar. Sometimes something like "Help", others "Toolbox", and commonly on en.wp "Languages".
You can see a few that might help you understand it at:
That's a textual+headers overview of the page that helps you view a page similarly to how a screen reader will present it to the user. (Which likewise in many cases will be similar to how a search engine / spider will conceptualize a page)
You can see the stuff inside the footer belending in with the last portlet header. This is how it will be treated towards a blind, etc... user.