What does PCIe x16 @x8 mean on the MSI MEG Z690 ACE EATX

What does PCIe x16 @x8 mean on the MSI MEG Z690 ACE EATX x8 slot Hi Can someone help me understand what PCIe x4 Slot means? boomerang jacks lost mines slot Btw, I'm pretty sure it's on the correct slot and I do not have any NVMe on the M2_1 slot or any at all for that matter

boomerang jacks lost mines slot hdx card in PCI-Express x8 card slot Pro Tools HDX & HD Native Systems

main demo slot slot Figure 1-5 shows the rear view of the PCIe Gen3 IO expansion drawer x8 Slot 3 P1-C3 PCle3, x8 Slot 4 P1-C4 PCle3, x16 Slot 5 P1-C5 PCle3, x8 It means it's a physical x16 slot and will take any size PCIe card, but it's only wired to x8