RTO

Recovery time objective is how quickly a service is supposed to be working again after it stops.

The number written in the plan is a statement of intent. The number that matters is the one you have actually achieved during a real test, and the two are frequently far apart, because plans assume the backups are good, the people are available, the documentation is accurate and the thing you need to restore onto still exists. An untested recovery time objective is a target, not a capability.