As a Joomla administrator you should be aware of security issues, how to maintain them, and how to make a backup or restore a backup. Learn more about Security & Maintenance.
- Knowledge about official security resources and how to subscribe to them.
https://vel.joomla.org/ - Making the site Search Engine Friendly (SEF URL’s, maintenance )
https://docs.joomla.org/Search_Engine_Friendly_URLs - (Two factor) authentication
https://docs.joomla.org/J3.x:Two_Factor_Authentication - Backups & Restoring backups.
https://docs.joomla.org/Backup - General knowledge. Check that the backup was successful.