
Explanation:
Box 1: Measurement
Telemetry/measurement is a stream of values sent from the device, typically from a sensor. For example, a sensor might report the ambient temperature.
Box 2: Property
The template can provide a writeable fan speed property
Properties represent point-in-time values. For example, a device can use a property to report the target temperature it's trying to reach. You can set writeable properties from IoT Central.
Box 3: Settings
Box 4: Command
You can call device commands from IoT Central. Commands optionally pass parameters to the device and receive a response from the device. For example, you can call a command to reboot a device in 10 seconds.
Reference:
https://docs.microsoft.com/en-us/azure/iot-central/core/howto-set-up-template