Part of macOS
fileproviderdCloud files
○ Leave it
Shows cloud storage such as iCloud Drive in Finder.
What it is
Lets iCloud Drive and other cloud services appear as folders in Finder.
If you stop it
macOS starts it again straight away. Leave it.
The verdict
○ Leave it. Part of macOS, or something that starts again by itself. You never need to close these.
In Activity Monitor
fileproviderdcom.apple.CloudDocs.iCloudDriveFileProvider
From Procession’s guide, in the words the app shows.