RS232 to TTL converter is used mainly to interchange the logic level of UART communication. The i-labz provides this board as a way to interface & there by convert RS232 output to TTL logic level or TTL logic level to RS232 level.
The RS232 to TTL converter need to be powered with +5V & ground connecters provided on the board can be connected using RS232 cable to the host system or module. Most of the interfacing & sensor modules comes with TTL outputs. I-labz has finger print scanner, Bluetooth, GSM Modem with TTL output format. So this RS232 to TTL converter can be used as an add on to interface with RS232 level supported devices.