Nature provides us "simple" hints about the nature of space!
One cannot see let alone touch space!
Yet let us consider two distinct stars within our milky way galaxy; something that is then invisible and untouchable has to be there in between the two, because if there were nothing the two would be in contact.
In a nutshell we human do not know what is space but we must conclude that something makes space, just to keep the celestial bodies separated from each other!
At least we know that gravitation "exists" in space; why would gravitation not be either an ingredient of space or space itself?
While we neither see nor feel space (a hint that induces us in believing that space is empty):
First, giving it a thought (above), we discover that space is something because something has to separate stars from stars and galaxies from galaxies.
Then we do feel the force of gravitation, a second hint of mother nature that indicates that either there is something in space or space is made of something.
So we can confidently claim that space is a volume that is either occupied by someting or a volume made of something.
Physics' concept of space is literally out of this world!
One of physics interpretation of space
In physics space is proven (first) to be absolute vacuum or absolutely empty
The famous experiments of Michelson and Morley of the late 1800’s proved "beyond any doubt" that light travels in absolute vacuum.
Since then physicists calculated that due to their speed should light waves travel through a medium, as sound waves do through air, that medium would have to be solid!
So in physics "space" is an absolute vacuum made of nothing!
And here is physics opposite interpretation of space
But in physics space is also filled with frantic energy!
Yet a (huge) controversy of physics is that the "quantum vacuum" is nothing but nothing! The quantum vacuum is instead filled with frantic energy, out of which material-particle / imaginary-anti-particle pairs can emerge.
Let's face it, physicists cannot have it both ways!
Space cannot be "absolute vacuum" to transmit light and "full of energy" to satisfy quantum theory!
Space in physics is another of those "dualities" that physicists acquit themselves with too easily!
And whether you are a layperson as this writer is or a scientist/physicist, the science of physics doesn't help you much! Physics doesn't answer the question: What is space?
Yet there is a simple solution
Believe it or not there is a simple solution to physics's dilemma!
That is, a solution not built on sophisticated yet irreconciliable mathematics!
And that solution is even simpler than identifying space to gravitation, as suggested above in this web page!
For your information, gravimotion's interpretation of Nature doesn't follow the path chosen in physics.
For instance that book explains why while the Michelson/Morley experiments make sense, physics interpretation of the experiments frankly errs, goes astray and escapes logic.