Why this message about 'can't open Documents'

[silverlakerCA]

Suddenly I'm getting this popup window that says I can't open Documents 'because the developer can't be verified'.
I am not trying to open Documents and have no idea what's causing this new message.
I'm attaching a screen shot.
Thanks in advance for your help.

 

[Slartibart]

There’s an app/program on your Mac named “Documents”. Why it is trying to run I do not know - maybe you try to open some file type which is linked to it?
The only app - I am aware of - named “Documents” is made by Readle - maybe you downloded and installed it? Anyway, use Spotlight to find and then delete it.
Of course if you are sure that’s an untampered file, you can follow this guide by Apple to run it on your Mac.