The application either simulates some of the interfaces, or uses the real hardware of your machine.
Device firmware from 1.3.42 and on even allows you to simulate the LoRa chip by sending and receiving Meshtastic packets via a local TCP port.
In this way, you can let multiple instances of the application communicate with each other as if they did via LoRa.
For instructions on how to use it, see the [interactive simulator](https://github.com/GUVWAF/Meshtasticator/blob/master/INTERACTIVE_SIM.md) that also emulates a wireless environment using simulated positions of the nodes.
Then after opening the firmware repository in Visual Studio Code, simply click on the PlatformIO extension in the left bar, select native and click on 'Build'.
This will generate the binary file 'program' which you can find in `.pio/build/native/`.
Once in this directory or when you copied the file to your current directory, launch the application with `./program`.
While you can interact with it in the same way as a normal device using a client that supports TCP connections, the application has its limitations. For example, rebooting is not implemented, so for some settings to apply you have to restart the application.