It employs the Udemy API to grab more info about the courses in you library and appends under each course:
Additionally it displays a thin colored strip at the bottom of the course card, from red (3.5 stars and below) to green (5 stars).
This should provide you with a good overview which course is worth its salt, and which course you might want to archive instead.
Note: If a course has stopped enrollment and isn't visible publicly anymore, no stats are available for that course.
To use user scripts you need to first install a user script manager. They come as extensions for various browsers:
After you have installed a user script manager, click here to install the user script and visit your Udemy course library 😃