This module is an HDMI to CSI Adapter commonly used for the Raspberry Pi.
It allows consuming/converting an HDMI stream (GO Pro, Canon, etc.) into a CSI camera stream supported by the Raspberry Pi.
For details see the manufacturers website
How to use
Connect the FPC cable of Raspberry Pi to the CSI interface of Raspberry Pi. The CSI interface of Pi 2B, 3B, 3B+ is located between the LAN port and HDMI port. The CSI interface of Pi 4 is placed between the HDMI1 interface and the audio jack. If you use Pi zero, the CSI interface is beside the Power port.