What Does PCIe x16 Mean?

I have 2 x16 pcie and 4 x1 slots I have 2 x8 cards in the x16 slots, but need basic display adapter functionality for debian xfce

Verilux® NVME Adapter PCIe x16 with Gel Pad, NVME or AHCI SSD to PCIE Adapter Card for Key M 2230, 2242, 2260, 2280 Size SSD, Support PCIe x4 x8

pcie slot pinout PCIEX16E-Q4S is PCIe x16 edge connector to four PCIe x16 Slot Interconnect Cabling solution

pcie 4 slot PCIe slots are used to connect graphics cards, sound cards, other interface cards and some