RPO (Recovery Point Objective) defines how much work you can afford to lose. If backups run once a night, in the worst case you lose a day of changes.
RTO (Recovery Time Objective) is how quickly a system must be running again after an incident. The business sets these two numbers, and they decide how often backups run and how recovery is done.
Example
A one-hour RPO for a shop’s database means backups must run every hour — a daily backup isn’t enough.