Exchangers are used to exchange (swap) blocks in the world with blocks in the player's inventory. When a block is shift right-clicked in the world it will be selected. Right-clicking another block in the world will swap it with the selected block, costing durability or Redstone Flux (RF).
Exchanges beyond the Wooden Exchanger can swap multiple blocks. Pressing the "," key (by default) will change the mode of the Exchanger, allowing for more blocks to be swapped at once. The blocks to be swapped will all be highlighted in the world. The Exchangers will only swap the exact same block right-clicked in a range, not all blocks in the range.