Space is of two types: real space and abstract space. In buddhism these are called produced space and unproduced space.
Space is produced when substance moves apart. Substance can move apart at the tantric level or the atomic level. Some larger types of substance such as cloth or putty can be seen to move apart when we pull it. Largely in the world, we think of produced space as when we move two containers aside, or rearrange our furniture. But if we think about it space is produced whenever we apply force to an object which distorts or tears its fabric or causes it to move!
Space is not empty for there is always a residual, or finer level, of substance between the separating objects or breaking structure. In philosophy produced space is never a void. A vacuum cannot exist in nature. The space produced is just of a less dense or categorically finer level of substance. But it is still substance. And no matter how far you divide material nature there will always be a finer level that you cannot see or detect.
Similarly produced space can be removed. Moving objects or substance together reduces or removes space. Where has the finer level of substance gone? That is for physics or tantric yogis to think about.
When we move we think we are moving through space. But this produced space is just a finer level of space which we can move through. It does not mean it is empty of substance whether it is air, outer space or the atomic space. Just that that level off substance permits the movements of more gross objects. This is what we mean when we refer to space in the common world or physics.
Unproduced space is abstract. It does not exist in the real world. It is produced by philosophy, or mathematics, as an ideal state in which dimension exists but substance does not. As such it is purely conceptual. It has no real correspondence in reality – though the temptation to apply pure mathematics to the real world has always been strong.
Pure mathematics exists in a conceptual, abstract framework. When we apply it to the real world for useful work we must leave the abstract world, and select an abstract mathematical concept to apply to the real world. As we do so we find we must bring in more and more variables to model the effects of finer levels of substance, such as air or wind or gravity. Or ignore those effects as too negligible for our problem.
In yoga we cannot ignore these effects and unproduced space is of no use to us. For we are interested in the perception of space not its cognition. If we mistake cognition for perception we will make the cardinal mistake of wrong understanding, and hence wrong view! If we meditate on unproduced space as itself we will never find emptiness. And the voidness we find will be a mistake, an incorrect cognition.