Picatinny is a raised rail with cross slots that accessories clamp onto. M-LOK is a slot system cut into the handguard, where accessories bolt on with a screw and a T-nut from behind. M-LOK keeps the forend slimmer, and Picatinny is quicker for clamp-on gear. These screws and nuts are for M-LOK only.
Thread the T-nut loosely onto the screw through the accessory, push the nut into the rail slot, then tighten. The nut turns a quarter turn and locks against the back of the slot. Snug it down firmly without cranking on it, and check it again after a few trips to the range.
You can, with a short Picatinny rail section that bolts into the M-LOK slots. That gives you a clamp-on spot for a bipod adapter or light without changing the handguard. Those rail sections mount with the same style of screw and T-nut that comes in this kit.