Blackstone Wall is a shaped crafting recipe that uses 6 items: 6 Blackstone. Place the ingredients exactly in the pattern shown above. The pattern can sit anywhere on the grid as long as its shape stays the same. It needs the full 3×3 grid, so you have to use a crafting table.
You need 6 Blackstone — 6 items in total, arranged as shown in the crafting grid. The recipe gives you 6× Blackstone Wall.
Yes. The recipe needs the full 3×3 grid, which only a crafting table offers.
It is a shaped recipe: the arrangement matters. You can shift the pattern around the grid, but the shape must stay the same.