iOS Backup Size plus Next Backup Size?
This means your current backup size on iCloud is 4.28GB.  The next time a backup is done it will add an additional 1.10GB.

4.28 + 1.10 = 5.38GB.  That will exceed the amount of space you have in iCloud.

You can reduce what's being backed-up or buy additional storage space in iCloud.  Check out this answer to a similar question for tips on what you can do.