Problem:
What are the aliases or filters for in the Backup Utility Tool?
Solution:
Aliases are used for email Forwarders, etc. The cPanel Alias Backup feature backs up your account settings for these aliases -- the fact that they exist and what they are -- NOT the entire contents of Forwarded email, etc. In other words, if you have an email Forwarder set up to forward email from you@yourdomain.com to you@yourisp.com, that's a setting you've created. The cPanel Alias Backup will back up that setting information so you can restore the Forwarder setting at some later date if you have changed or lost it. It will not back up the actual contents, mail, or files of any email account.
Filters are used for filtering email for spam, etc. If you have a lot of email filters set up, you can back them up. If at a later date you delete the email filters and then need to restore them, you can do so by Restoring a Filter Backup you have made with the cPanel Filter Backup feature. For example, if you have 20 email Filters set up and you lose these settings for some reason, it would be a difficult to remember exactly what filters you had setup. You could instead use the cPanel Filter Restore to restore all prior filters at the click of a button.
cPanel Alias/Filter Backups allow you to selectively backup and restore mail aliases and filters for either your main domain or specific subdomains in your account, without affecting any of the rest of your site.