What does the X4 mean in an PCIe Gen X4 NVME drive?

Looking at Amazon there is PCIe Gen 3 NVME and PCIe Gen 4 NVME for sale I don't see this even mentioned on the Wikipedia page for NVM Express

NVMe SSDs, even the last-gen PCIe Gen 3-based NVMe SSDs, are immensely faster than this Once you start pushing further beyond into NVMe Gen 4

nvme pcie 40 in 30 slot According to the above comparison of PCIe Gen 4 vs Gen 3 slots, we can conclude that PCIe is the winner However, if your computer is

nvme slot vs m2 5 Place that in PCIe slot 4 which is a PCIe generation 3 slot with x8 electrical lanes The card is PCIe3 x4 Note that the