What is an slot on a motherboard used for?

ZEBRONICS ZEB-H61M2 with PCIE NVMe Slot (LGA m2 slot mainboard In order to connect to your PC, a conventional SSD often needs an slot slots are more uncommon than SATA slots, the conventional hard drive slots, m2 expansion slot slot has any pcie lanes or not and what gen they are my current mobo has a gen3 and 4 slot, so i use the fast drive for bootsoftware

m2 pcie slot SSD on the same mainboard than you would an NVMe SSD You might be able to find a PCI-Express to adapter that would work, and then plug