Consciousness is generally considered to be the state of the mind in which humans know and perceive what's going on in the world. This consciousness is generally considered to be an activity of the brain. This is the scientific view, but science is still unable to fully understand consciousness and how the brain generates it. Consciousness is considered to be a state of the mind, and the mind is generated by the brain somehow.
I'm certainly going to diverge from that perspective here. Rather than consciousness being in the mind and the mind being in the body, from the Non-Duality understanding it's the other way around. The mind, the body and the world appear within consciousness. And it's not just the Non-Duality understanding, it is the understanding of direct experience. All that you have ever experienced of the mind, the body and the world has been in consciousness. Without consciousness, the mind, the body and the world would not appear.
If you hear a sound it is within consciousness. If you open your eyes and look around, this moving image of the world appears in consciousness. The thoughts that float through the mind - "What shall I have for dinner?" or, "I must remember to send that message" - appear in consciousness. Your whole world picture, and all that you know about the world, is right here in consciousness. The hillside that you can see far away, that is perceived right here in consciousness. The sound of the plane flying overhead, that's perceived right here in consciousness. All that you know about your body is perceived in consciousness - the view of your hands, arms, legs and feet, the image you see in the mirror, the feelings of sadness and joy, the sensations of pain or discomfort, the softness of textures, and the tastes of your favourite foods, are all perceived in consciousness.
The mind and thinking is perceived in consciousness. Not only are the thoughts and images of the mind perceived in consciousness, but also the sense of 'I'. There is a sense of 'I am this', 'I do this', and 'I have this' that develops in the human mind, and this is perceived in consciousness.
Truly Consciousness is the still, silent, formless, dimensionless intelligence in which the world appears. The world of forms and solidity, of movement and sound, depth, distance, and change, appears within Consciousness. Consciousness, being formless and dimensionless, is without limits. The sensation and experience of limits appears within Infinite Consciousness. This sense of limits gives rise to the belief of separation and identity. The ego appears in the mind, but is perceived in Consciousness.
Withdrawing from the distractions of this apparently moving, changing world, and withdrawing from the chatter of the mind, Consciousness is known to be just the pure, effortless, unchanging presence in which the world seems to happen. It only seems to happen. Nothing is really done. Consciousness doesn't walk down the street or take a plane to Spain. Consciousness has no arms or legs. It is formless. Forms appear within Consciousness, similar to how dreams appear within the mind.
It might help to imagine nothing. Well, really it's more about not imagining anything, closing your eyes and letting go of thoughts, feelings, ideas and concepts, and just letting the mind be quiet for a short time.... You know that you're here. You are Consciousness. You are alive. You exist. But you aren't over there somewhere. There is no distance or limits. 'You' can't be found or defined. But you know you are aware. This is the shared core of all that is experienced. It is the Self Aware Consciousness. It has no 'substance', form or identity. It is this in which form and identity are experienced.
Open your eyes again and the world seems to fill Consciousness, but Consciousness remains just as it is.