This is custom 5x5cm Arduino UNO board that allows simple connection to HUB75 interface LED displays.
If you are not familiar with such displays you can buy one from Adafruit 16X32 RGB LED MATRIX PANEL
HUB75 interface LED displays usually comes with flat cable for data and power cable. So after you soldered this PCB all you need to do is to connect power cable to screw terminal. and plug flat cable to PCB and LED display. Pinout compatible with Adafruit "RGB matrix Panel" library, but I wanted to understand how HUB75 interface works. So I wrote my own library. Five free pins can be used to connect sensors or other devices.