Sprint demo is showcasing all the completed stories those that met definition of done.
Collect all such completed stories from the scrum board and for each one it is expected to provide scope and intentions. Explanation of how this story fits into a feature or in the product. Few are some points to consider when having demo.
The sprint demo is invaluable for keeping stakeholders up to speed with the progress of product development. It allows them to feedback and discuss with the Product Owner and Scrum team any possible amendments to the Product Backlog which would help to maximise value.
Such discussions can inform the planning of the next sprint and the contents of the next sprint backlog. They will often result in stories being added further down the product backlog too.