API requests are calculated based on the requests you send. For example, if you want do download an element of the TODO list, you’ll perform 1 API request. The backend will send you the response that, of course, will not be counted as it’s not a request.
Also, considering your example, if a user performs 10 updates in 1 day, that’s = 10 API request. If 10 users do the same, that’s 100 API requests.
Hope it helps.