What exactly does the spec “PCIe x16 slot ” mean?

What exactly does the spec “PCIe x16 slot ” mean? 4x pcie slot Most recent PC's motherboards have PCIe slots just for PCIe cards to be installed in the corresponding PCIe slot x, PCIe , and PCIe 5 4x4 joker slot PCI-e 4X PCI slot expansion box is designed to expand from an existing PCI Express slot on your computer system The PCI Slots are plug and play expansion

4x4 joker slot PCI Express slots are one of the essential technologies that exist on a motherboard PCIe slots are utilized by various performance

4x4 slot pg PCI-e 4X PCI slot expansion box is designed to expand from an existing PCI Express slot on your computer system The PCI Slots are plug and play expansion  Difference between PCIe Gen 3 and PCIe Gen 4 With options for 1x, 2x, 4x, 8x, and 16x slot configurations, PCI Express doubles the speed