What is camera matrix and projection matrix?

https://github.com/epan-utbm/utbm_robocar_dataset/blob/3e229a80c2fe13ef82f7e63bb65324e5de4d1e7c/camera_info/bb_xb3_left.yaml#L4

Hi, I an confused by the camera matrix and projection matrix. What is the relationship between them and camera Intrinsics