Source: Google
If you're working on a presentation with a colleague or classmate, it'll be much easier to follow along with the changes made to your Google Slides file. The app will let you "follow" a collaborator to see what they're working on. You can click on their avatar in the Slides toolbar to see what slide they're on. You can also stop following them by clicking on the avatar again. You will also stop following the collaborator if they refresh or leave the presentation, when you make edits yourself, click on a different slide, or enter the Slideshow mode.
The feature is already rolling out for all Google Workspace customers, G Suite Basic and Business customers, and those with personal Google accounts.