RTO (Recovery Time Objective) is defined based on how fast you want to resume your operations after a disruption, while RPO (Recovery Point Objective) is defined based on how much data you can afford to lose due to a disruption.
For example, if an application has an RTO of 1 day and an RPO of 4 hours, it means that this application can be recovered (resume normal operation) in one day, but the information from the last 4 hours before the interruption occurred will be lost.
Business Continuity strategies refer to high-level actions to be developed to achieve defined continuity objectives.
For example, to ensure the objective of recovering operations in a defined timeframe, the strategy adopted may be the use of an alternative site. Another example is a backup strategy (which could be incremental, differential, etc.).
Testing and exercising are activities performed to find what doesn’t work in your business continuity in a controlled situation. In other words, when you lack real incidents, you create simulated ones to be able to improve your plans.
These articles will provide you a further explanation about these concepts: