When the IoT Hub is created you will get an endpoint hosted in Azure. This is the target for the JSON events being generated from the mobile device.
Azure IoT Hubs are more complex than an Azure Event Hub, perform a lot more device based functions and also have stronger security capability. However, operationally they work pretty much the same.
If you want to learn more about the differences between the two Hubs then this is a great article – https://docs.microsoft.com/en-us/azure/iot-hub/iot-hub-compare-event-hubs
It’s a neat tutorial for a fun weekend project.