The transposer bridges the gap between redstone controlled hoppers and Robot, allowing computer-controlled transferal of items and fluids between adjacent blocks.
Note that this block has no internal inventory.
Besides moving things around, it can also be used to inspect the contents of the adjacent inventories, like an Adapter with an inventory contoller could, and the contents of adjacent tanks, like and adapter with a Tank Controller could.
The component proxy on a computer provides an api as described here