As the scrum master, your main roles are coach, leader and facilitator. The scrum master is a scrum expert and it is their responsibility to ensure that the scrum process’ are being executed and performed correctly. They facilitate scrum by encouraging self organization, creativity and empowering the development team. They keep the team motivated and accountable for the work they committed to and also work to improve engineering practices so each increment is potentially shippable at the end of the sprint.
The scrum master is also responsible for teaching the product owner to meet their objectives through scrum and maximize ROI. They remove any barriers of communication between the product owner and the development team so the product owner can drive the team directly. While also removing any obstacles affecting the team and protecting them from any interferences or additional work during the sprint.
The scrum master is a servant leader and leads by supporting the team rather than micromanaging them. The scrum master understands that by allowing the team to feel pride and ownership of their work will result in the best productivity overall.