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

PCIe Gen x 16 Vertical GPU: up to 4 slots; horizontal GPU: 3 slots drive mounts Vertical GPU: 3 x ” SSD; horizontal SFF GPU: 6 x ” SSD

2 Slot is from the Ryzen 7 5700G then it will only support PCIe Found this tech site that explains that a Motherboard can have both PCIe and slots:

genting casino slot games free download 2 slots — supporting both PCIe and — that allow you to expand your system with high-performance SSD storage Designed for the latest generation of NVMe

genie slot Previous gen SSDs had max speeds of up to 3500MBs, while the new generation claims speeds up to 5000MBs Today, we'll be putting several new