It's possible what you're seeing is not a folder called "File" on your login screen, but instead a notification from the "File process" (I don't know the exact name of the process and the exact name might depend on which desktop environment you're using.)
Are all of the following true:
You were previously logged in but did not log out. Instead, you locked the screen or had suspended somehow so that your user is still active.
Before you locked your screen, you had started a procedure that was related to the "File process". For example, you might have initiated:
a. Copying many files.
b. Moved many files.
c. Deleted many files.
And whatever you started hadn't finished when you locked your screen.
If so, then it's possible that it finished while you were locked out and what you're seeing is just a notification. The "2" just means you have two notifications.
I'm using Gnome and after I log in, I click on the date at the top menu and the notifications are shown. (If I remember correctly, they also appear briefly once I unlock the screen.) How you can see them will depend on your desktop environment.
(And yes, other notifications are possible. If you had a web browser open when you locked the screen and you received notifications from a web page while you were away (i.e., like YouTube, etc.), then you will see it at the login screen as well. It will indicate the web browser that you were using.)
I hope this helps!
