This is a **DS18B20** emulator, i.e. it turns an Arduino Uno into a device roughly equivalent to an actual DS18B20 temperature sensor. Excepted in this sample it doesn't actually sense temperature (because the Arduino lacks the hardware for this), it just returns 42 as if that was the expected answer.
If you don't use an Arduino Uno, you may need to adjust which pin you connect as the data line (it needs to have hardware interrupts), and make the corresponding change in the example source code. A few microcontrollers are compatible with the library, check the full list in [the documentation](../../documentation.md).