What is the "iCloud Drive (Archive)” folder I see in my User folder on my Mac? Can I delete it?

See the following from Add your Desktop and Documents files to iCloud Drive - Apple Support

If you turn off iCloud Drive or sign out of iCloud, you have the option to keep a local copy of your files that are in iCloud Drive. Whether you decide to keep a local copy or not, a new Desktop and Documents folder is created in your home folder. If you choose to keep a local copy, your files in iCloud Drive are copied to a folder called iCloud Drive (Archive) in your home folder. Then you have the option to move any files that were in your iCloud Desktop and Documents, back to your new local Desktop and Documents.

See the article https://support.apple.com/guide/icloud/what-is-icloud-drive-mmd0b4a7f5e8/icloud

With iCloud Drive, you can securely store your files in iCloud, and access them on iCloud.com and your iOS device, iPadOS device, Mac, and Windows computer. You can also have all the files in the Desktop and Documents folders on your Mac stored automatically in iCloud Drive. That way, you can save files right where you usually keep them on your Mac, and they become available on iCloud.com and all your devices .

if you open system preferences > iCloud and uncheck the box of iCloud Drive a pop up window appears , showing to keep a copy of documents , and remove from the Mac .

( a ) if you had clicked on keep a copy , they will be archived in home folder that can be viewed by clicking on finder in the dock , take cursor on top menu bar > Go > Home > your user name > iCloud Drive ( Archive ) .

You should not delete it , these are second copies of files stored in desktops and documents ( helps in emergency situations ) , you have set up time machine and its backing up suppose time machine back up fails or stuck https://support.apple.com/en-in/guide/mac-help/mh15653/10.14/mac/10.14

Then these files are accessed and stored in iCloud Drive ( archive ) .