Coir is compressed, ground, coconut fiber. (Note: A Bale is equal to about 7-8 Coir Bricks) Soaking a brick in a couple gallons of water (ideally with some added Superthrive or Dyna Grow KLN) and the media will fluff up to make a good growing media for many plants.
Coco Coir is great for water holding capacity yet these materials also provide plenty of aeration and drainage.