This board translates RS232 signals to TTL. Originally it was designed to fit a power supply to give 5V to set01_01 microcontroller board. Nowadays power supply components are not mounted because USB is able to supply 5V and final price is minimized.
Connector 5x2 links to desktop serial port using set01_03_B cable. Connector 4x2 links to UART using set03_11 cable.