All we know are objects. The existence of a subject (eg. the witness or consciousness/awareness) is an inference, a belief.
Some versed in advaita-speak then counter by asking ‘Who/what is it that knows this?’. The problem is that the very question ‘who knows’ is based on the belief that there must be a subject, a knower.
It’s similar to an argument for the existence of God in which people say look at all this marvelous creation, who is the creator? Of course, the assumption is there must be a creator, a subject who creates, and this is a false assumption (ie. it is based on false logic).
Inference does not always work as a way of understanding and knowing things, as it is only as good as the logic that underpins it. We could go on with other examples of this faulty logic in which the notions of a subject is unnecessarily believed in: Who blows the wind? Who quakes the earth? Who grows the trees?
Now strictly speaking, we are not saying there is no subject, just as we are not saying there is no God. We are just saying there is no evidence for either of these, and therefore no need to believe one way or the other in a subject.
What we are left with is ‘what is’ or ‘life’ or ‘experience’. It all just happens. It’s already happening. Everything is a part of IT.
So simple, direct, and already fully known (seen), but in essence it is mysterious and uncapturable by words.
There is a great freedom in seeing this.