Nirguna Brahman

Nirguna brahman is the still reality according to Advaita

It is a concept representing ultimate divinity

From the still reality of nirguna brahman which is the ultimate divinity two other realities called saguna brahman and maya are automatically projected. Saguna brahman typifies truth and maya typifies illusion.

The world is supposed to be the creation of saguna brahman by using maya. So on truth illusion is superimposed and the world is full of half truths in the sense because of maya, the full truth is not evident. The purpose of each soul is to figure out the hidden truth and see the whole. Then it's knowledge becomes the same as brahman and the soul merges with it.