Skyberry Bushes are naturally occurring blocks in the Nether that spawn Skyberries.
The Skyberry Bush is an easily transportable block. They infinitely spawn Skyberries. You need to tap the bush in order for it to drop the Skyberry. The Skyberries can be easily seen on the full-size (grown) bushes, as they appear as teal/cyan dots. Only harvest when you see the Skyberries on it.
When transplanted, they will need to grow to their full form to spawn Skyberries. They need to be placed on netherrack or Tainted Soil.
You can use bonemeal on the bush to make it grow through the stages faster as well as produce another bush on top once that bush is fully grown.