It's an adapter card to join the rileym65 / Pico/Elf V2 COSMAC CDP1802 Microcomputer to the fourstix / PicoElfTMS9118VIOCard (TMS 9118 video, Hex keypad, TIL311 data displays).
The bridge was designed to use whatever gender of sockets are needed to join a Pico/Elf V2 with a PicoElfTMS9118VIOCard. Long pin sockets can be used to extend the card so that additional IDE type cables or cards can be stacked above the main boards.
Information about the Pico ELF Version 2 COSMAC CDP1802 Microcomputer can be found at the ELF Emulation Website
Files and information about the TMS 9118 Video Card with Hex Readouts and Keypad can be found here: PicoElfTMS9118VIOCard