The JDY-40 is a 2.4GHz RF transceiver module (similar to nRF24L01 but simpler) that operates as a transparent wireless serial bridge. Unlike Bluetooth, you don't need pairing; unlike WiFi, you don't need an IP address. You simply type on Serial on one end, and it appears on the other.
: For a look at how the JDY-40 is used in professional research, the peer-reviewed paper "Wireless Data Acquisition System with Feedback Function" in MDPI details its integration into a data acquisition sensor, highlighting its 3.3V power requirements and energy-efficient sleep modes. Practical Implementation Resources jdy40 arduino example best