Amazonite Block is one of the many Decoration Blocks added by the Soul Forest Dimension. It can also be called a Storage Block. The Amazonite Block emits light after its placed, it doesn't need a redstone signal for that.
Aswell as most of the Decoration Blocks this block is crafted with 9x Amazonite Gems. After an Amazonite Block is made, its content (the gems) can be easily re-obtained by simply placing the block in a crafting table.
As the block emits light it can be used in a lot of ways, a good thing about it is that it doesn't need a redstone signal to emit light.
A different use, but most likely a much more usefull function is the fact that you can easily store a lot of Amazonite Gems by turning them into blocks.