Literally this means : WordPress Chronos.
In the hosting world, cron is a tool used fire functions and programs at set intervals. WP Cron is the built in simulation of external cron jobs – but are formed from within. This can be handy in many instances. But, because WP Cron works on the triggering of WordPress loading itself – it can not be depended on for sites with no traffic. (for example, if you want daily backups of your staging site despite no one visiting it, an external cron job would be best)