is this used for? I've tried to search for a tutorial and just get generic information. I dont own a Mac, so not sure how, or what, I'd use this Files App for...
If you want to know how to use it on an iPad, the second video on this page is a good intro: https://www.apple.com/ipad/new-way/#mn_p
(Maybe also watch the multi-touch video for another use for the Files app.)
I haven't really used it yet on my iPhone.