Wooden Slabs are a half-block made entirely of any kind of Wood (match type). Slabs are decorative blocks that can make houses or structures look better. They can be used as a longer alternative to Stairs, as the player and mobs automatically walk on the top of half-blocks without jumping. They can also be used as an alternative to Fences, as you can create a one-and-a-half hit-box similar to fences by placing a slab on top of a regular block.
Wooden Slabs are crafted with 3 wood Planks in a horizontal line. This creates 6 wooden slabs. Each wood type has the same slab, 3 oak wood has 6 oak wood slabs, 3 spruce wood would have 6 spruce slabs, Etc.