The package includes an infrared keypad (similar to a simple TV remote) and an infrared receiver. You hook the receiver up to an Arduino then use the Arduino IR library to decode which key was pressed on the transmitter. Very quick, easy, and inexpensive way to get basic remote control functions into a project.
The remote requires a CR2025 button cell battery which is not included. These are commonly available in stores, because they are used in electronic devices.
We found this tutorial online, and there are many others.