Wanderlust step 13/14/15

I have successfully completed all the steps 6 to 17 to get the data from foursquare, and I am now trying to understand better what is happening in these exercises.
At step 13, I don’t understand why the GET request sent with fetch() gives us only the url we asked for (urlToFetch) and not the 10 venues we are looking for? So it’s not fetch() that will retrieve the information requested in the foursquare API?
It would be the json() method that would go to this url to look for the 10 places?
Thank you in advance for these clarifications.