Why can't I open iCloud files on my MacBook Pro?

On MacBookPro, since earlier today I have been unable to open files I saved on ICloud. I click on Finder, and Alongside the ICloud Drive name, when I click on whichever file, there appears a round 'clock' which appears to be 'clocking down' minutes but doesn't actually move. If I click on that an Information sign is displayed.

I've shut the MacBook Pro down and reopened with no luck. I'm not hugely computer literate so words of one syllable please!!

Please help.

[Re-Titled by Moderator]