You don’t need to tell a huge story or prepare a perfect PowerPoint presentation. The point is to present your work in progress.
Show what the challenges are and how you will solve them through design.
If you’ve done showcases before, it’s also helpful to summarize the results and takeaways and pick up where you left off for the current showcase.
Also, think about any open questions you have that you would like to have answered by the UX showcase.
I run showcases in a WIP FigJam file that captures the key considerations and designs. Often this is a copy of the original file, to which I also give the team direct access after the showcase (24h edit rights in FigJam), so everyone can leave their input directly in the design.
It’s up to you whether you send out an agenda before the showcase and, for example, already share the open questions in it so that the participants can think about them, or whether you share everything during the showcase. If you have very little time for the showcase, it is a good idea to include the questions in the invitation.