Release planning provides answers to these questions;
When can we release the minimum viable product (MVP)?
How many sprints are required?
Will there be parallel sprints?
Which feature will be done in which sprint?
How many releases have we planned?
What are the dependencies?
When will this project get over?
Release planning is done by the product owner with the help of technical people and functional experts before the formal kick off of the project and continues with the refinements at the end of every sprint or whenever new requirements are identified.