When you open a pull request against your source repository of your course, a PR app will be created.
The PR app deployed allows you to preview the changes made to the course and check the deployment status of the changes.
Accesss PR app deployments
You can access the PR apps from the pull request created by clicking on the links shown with deployments.
Once you open the PR apps, you can see the list courses that are being deployed along with their status.
You can check the details of deployment of individual courses and also preview the changes made.
PR apps will list only the courses which are modified.