Osho tries to explain why Advaita defines Brahman as not two or why they did say it is one.
Advaita means literally non-duality, not two. They could have said one, but the Upanishads never use the word ‘one.’ They say non-duality not two. And this is very significant, because if you say one, the two is implied, it becomes a positive statement. If you say there is only one, You are asserting something positive.
The moment you say one, the two is implied, because one can exist only by the side of two. So Upanishads, never say that the Brahman is one, the truth is one. Rather they use a negative term; they say he is not two. So one is implied, but not directly asserted.
Secondly, about the total we cannot assert anything positive, we cannot say what it is. At the most we can say what it is not, we can negate. We cannot say directly, because once we say something directly, it becomes defining, it becomes a limitation. When you simply say it is not two there is no boundary – the implication is infinite.
You cannot point to the Brahman with a finger, because your finger will become a limitation. Then Brahman will be where your finger is pointing and nowhere else.