With the activity feed in each project (an exclusive feature for Pro workspaces), you can keep tabs on who's working in the project and what kind of changes they're making. When multiple people are working inside a project, activity feeds are great for keeping everyone organized and giving help where it's most needed.
To open up the activity feed pane, open up any project, then open the project settings menu (click the menu icon in the upper left of the screen).
Click on "Activity" in the sidebar to see all kinds of project changes—adding new elements, editing profiles, updating views, creating new maps, etc. It will also show you who made those edits and when.
Activity feeds are an exclusive feature for Pro workspaces.
If you transfer an existing project into a Pro workspace, its activity feed will show all historical activity (not just the activity that happens after you transfer the project).