Your backup will not work when this message is displayed!
You have tried to use your site's root as your backup output directory directory. This setting is not compatible with the way Akeeba Backup / Akeeba Solo works and will lead to backup failure and/or incomplete backups.
Akeeba Backup / Akeeba Solo automatically tries to exclude the files and directories contained inside the backup output directory. This allows it to effectively avoid "backing up the backups" or entering an infinite loop, i.e. trying to include a backup archive file which constantly grows in size.
To fix this please go to the Configuration page and chose a different output directory.