As a Product Owner you are responsible for the business value of the project within the team.
Make compliance statement for all customer requirements that apply to the team.
Agree with the customer on all compliance statements made on customer requirements that apply to the team.
Agree with the customer on all user stories and acceptance tests being defined by the team.
Accept or reject work results, i.e. use stories implemented in a sprint.
Lead the definition of user stories for sprint backlog and product backlog.
Lead the prioritisation of user stories.
Lead the definition of sprint backlog.
Support team in clarification of user stories, explain feature/business values, motivate prioritisation.