How do I see the data in iCloud?

On an iPhone or other iOS device, iCloud is designed to be viewed by using the apps on the device (e.g., the Files app for iCloud Drive, the Photos app for iCloud Photos, the Notes app for notes, etc.).

You can also use an internet browser on a computer and log into icloud.com.

Also note that while you can view synced data as described above, it is not possible to view the contents of an iCloud Backup. You can only use the backup to do a full restore of a device or to setup a new device.

The following may also help: https://support.apple.com/en-us/HT204247

The only thing you can do with an iCloud Backup is use it to restore or set up a device.

You can delete the entire backup as described in Manage your iCloud storage - Apple Support

You can also go to Settings > [username] > iCloud > Manage Storage > Backups > [device name] > Choose data to back up and turn off things that you don't want to back up.