What are all these files on my Mac?
You're in a search screen and it's currently listing all of the files on "This Mac" (your Mac).  It's literally (not figuratively) every single one of your files listed alphabetically in a search window; it's nothing harmful.



Just close out of the search and you'll be fine.  You might want to take a quick read of the Apple document, Get to know the Finder on your Mac.