RPO describes the point in time to which data must be restored to successfully resume processing. But i don't understand why it's related with the time between last backup and when an disaster occured. Can u explain this and give some examples.
I will give you an easy example. Imagine that you have established in your backup policy that every day at 22:00pm a full backup is performed. Monday the backup is performed, but Tuesday there is a problem with all information system at 10:00am, and you need to restore information. What information? The information saved in the last backup (Monday at 22:00pm). So, in this case you would lose the information developed after Monday 22:00pm until Tuesday 10:00am. And obviously, it is related with the time, because you can only restore the information saved in the last backup (at 22:00pm).