Good overview (available for free after login): https://systemdesignschool.io/problems/yelp/solution
Good video: https://www.youtube.com/watch?v=yz1jtze4qr8
The location proximity service is the main thing to understand (and challenging). Here are some resources for that:
High level summary: https://www.youtube.com/watch?v=M4lR_Va97cQ&t=884s
To get a better intuition: http://youtube.com/watch?v=LHuhvvlFxA0