This is an application for Mac OS X to enable use of the cheap USB-to-RS232 Serial cables based on the WinChipHead USB to Serial/Parallel/I2C chip.
It functions as a simple serial terminal application, i.e. the user can type on the keyboard and the charcters are sent to the serial line. Likewise, data received on the serial line is shown in the application's window. There are also small indicators of the status of the handshake lines (DTR, RTS, etc.)