What is a cron job?
Cron job is a scheduling utility that lets you set a recurring command, or script, to be performed at specified times and intervals. They are very handy for handling mundane, recurring tasks. For example, you probably don’t want to hold onto every log or file that gets stored in a folder as they will eventually take up storage space and may not be necessary to retain. For this, you can set up a cron job to remove files that are older than 3 months, as an example.
Adding a new cron job
For a specified server, select Cron Jobs and then select the Add button to add a new cron job. Add a name to refer to the job as, a command, enter the user you want to perform the action (typically cleaver, root, or another user you configured -- be very careful using root user), select the frequency, and then select Schedule to add the cron job.
The frequency section uses cron job formatting but includes hint text beneath it that lets you know how the job will be scheduled in clear words. See the following wikipedia article on how you can work with the scheduling format if you are unfamiliar with it. https://en.wikipedia.org/wiki/Cron