An API is the part of your app that is directly accessed by agents outside your app. But what is your app?
An application (app) can be subdivided into any number of subdivisions using any criteria imaginable, and each may be considered an app unto itself.
For example, I might decide that my app is the combination of both program running on a server, and a user interface program running on his machine, and that the internet communication between both is also part of my app. The API of such app is the client's interface the human or robot uses.
Or, I could say I have 2 separate apps, one is the server app, one is the client app, and the internet communication is not part of either. Besides the client's API now I also have the server API which receives requests from the client.
Then I could say my server actually consists of 4 apps, each of which handles a different sub-service. Each of them will have an API to communicate with each other.
Ultimately, I could even consider each individual function to be a separate app. The API of a function is how it's called (its name and arguments, in the correct format). You may consider the return format as well (or not).
In your example you mention 3 routes. If you consider each service they target as a separate app, they yes, you have 3 APIs. If you are thinking about it as a single whole, you have 1 API. It all depends on what you consider to be "the app", the API is referring to.