This is an HPE NVMe Interface PCIe Controller Board (also called PCIe NVMe Bridge Controller Card or Express Bay Bridge Board).

It is a PCIe 3.0 x16 full-height card designed to enable NVMe (U.2) drive support in certain HPE ProLiant servers, particularly the HPE ProLiant DL580 Gen9. It provides connectors (typically three internal 68-pin) for controlling NVMe drives via PCIe lanes.