What does x4 bandwidth mean on a PCIe x16 slot?

can you put a pcie x4 in a x16 slot   Dan candy pop slot

x' denotes how many PCIe lanes the slot has As you will find out in this

Both the blue slots are PCIe x16 The difference is that the 2nd PCIe 16x is capable of wiring If you have the option of multiple slots where at least one supports PCIe, it's worth considering your secondary slot for an SSD upgrade When combined with

kitty glitter slot machine free play 2 NVME or AHCI SSD to PCIE Adapter Card for Key M 2230, 2242, 2260, 2280 Size SSD, Support PCIe x4 x8 x16 Slot  Both the blue slots are PCIe x16 The difference is that the 2nd PCIe 16x is capable of wiring