Cron jobs allow you to automate certain commands or scripts on your server to complete repetitive tasks automatically. A cron job allows you to run a certain command at times set by the job. For example, you could set a cron job to delete temporary files every week so that your disk space is not being used up by those files.
It is important that you familiarize yourself with how cron jobs work. You need to have a good knowledge of Linux commands before you can use cron jobs effectively, especially when using the "Advanced (Unix Style)." Check your script with your hosting administrator before adding a cron job.