Your backup will not work when this message is displayed!
Akeeba Backup or Akeeba Solo has detected that you have instructed it to place the backup archives and log files inside a subdirectory of its main installation directory where it keeps its own system files.
It is not a good idea mixing your backup archive and log files with system files belonging to the backup software.
An update could remove those folders at any time.
Additionally, there is no guarantee that the naming of your backup archives will not cause an accidental problem to the backup engine itself.
Please go to the Configuration page and select a different backup output directory. The best choice is creating a directory next to and outside your site's web root folder. Your second best and easiest choice is using the default backup output directory.