Nether Brick Slabs are half-height versions of nether bricks block. They can generate naturally in Nether fortresses and can also be crafted by the player. You can pick them up by mining them with a pickaxe.
A Nether Brick Slab (via screenshot)
Nether brick slabs are naturally generated in nether fortresses and can be picked up by players. They can be broken with or without any tool but nothing will be dropped if a pickaxe is not used.
Players can craft nether brick slabs themselves by placing three nether bricks next to each other in the crafting grid. You can also place nether bricks into a stonecutter to make nether brick slabs.
Making nether brick slabs from nether brick blocks (via screenshot)
Nether brick slabs behave like regular slabs and are transparent to light and mobs. Slabs are seen as full blocks by mobs when they are pathfinding. Two slabs placed on top of each other make a full block of nether brick. These slabs don't have any specific use and cannot be used as a substitute for crafting recipes that require stone slabs of any kind.
Crafting chiseled nether bricks with nether brick slabs (via screenshot)
Nether brick slabs are a variant of regular slabs that originate from nether bricks. Since they can be made and found quite easily, they are quite commonly used as decorative or building blocks by players.
A. You can make a nether brick slab by either placing 3 nether bricks in a straight horizontal line in the crafting grid or by using a stone cutter to cut the nether brick.
A. Nether fortress mobs such as blazes and wither skeletons can spawn on nether brick slabs if their requirements are met.
A. Nether brick slabs can be used for decorative or building purposes.