1 Paris: We're approaching Bune. Prepare to exit hyperspace.
2 Serron: That was quick.
3 Paris: Time flies when you're having fun.
4 Iki Piki: Or in sheer terror.

I could have sworn I mentioned this in a previous annotation, but I couldn't find it, so:

My original conception of hyperspace in this universe is that you shouldn't be able to see stars while in hyperspace. But that'd look dull as a background and somewhere along the way when they first went into hyperspace I simply pasted a starfield background in as usual - and I've continued to do so ever since.

So now my conception of this particular instance of hyperspace is that it's an alternate dimension through which the starship travels and in which travel distances don't match the corresponding distances in realspace, but apart from that property it's actually just a normal space, full of matter and energy, and stars and planets and stuff. So there are potentially beings who evolved in hyperspace and for whom the normal universe of Spanners, Serron, et al. is a "hyperspace".

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2016-06-08 Rerun commentary: Between this strip's annotation, and those of #1258 and #2059, I think I've said most of what I want to say about how hyperspace works in this setting.

Except I don't think I've ever explained the concept of hyperspace skew. The word "skew" or "skewing" is used consistently by the characters in this story to mean the transition or act of transitioning between realspace (i.e. the normal space we inhabit) and hyperspace. This is because hyperspace in this setting is a set of three spatial dimensions which are all mutually orthogonal to the standard three spatial dimensions. Normally you can't detect or interact with them. But by using a hyperspace skew generator, you can rotate something, such a ship and everything aboard, into those three dimensions.

Imagine a table surface, and a flat piece of paper lying on the surface. The paper inhabits the two-dimensional (x, y) space of the table surface - well, not really, since it has a finite thickness, but you can imagine an idealised two-dimensional sheet with length (x) and breadth (y), but no thickness (z) at all. Anyway, there is a third dimension (height, z), that the paper can't inhabit or experience. But by rotating, or skewing, the paper to bring it to a vertical position, you take the paper out of one of the horizontal dimensions and put it into the vertical dimension. So for example it now has length (x) and thickness (z), but no breadth (y) at all.

This is not a perfect analogy, since it has length (x) in both positions. You could imagine an infinitely thin spaghetti strand, which only has length (x) but no breadth (y) or height (z), skewing into a position where it now has height (z) but no breadth (y) or length (x).

Similarly, a spaceship has length (x), breadth (y), and thickness (z), but no hyperlength (α), hyperbreadth (β), or hyperthickness (γ). Using a hyperspace skew generator, it can skew, or rotate, out of those three dimensions and into the hyperdimensions, so now it has no length (x), breadth (y), or thickness (z), but does have hyperlength (α), hyperbreadth (β), and hyperthickness (γ). The result is that it can't see realspace, be seen from realspace, or interact with realspace any more, but it can see, be seen, and interact with hyperspace.

In this skewed state, the ship travels through hyperspace using its engines like normal. After traversing some distance for a few hours or days or whatever, it can skew back into realspace, and it may be hundreds of light years from where it skewed into hyperspace. The details of the distances traversed depend on a bunch of mathematics too detailed to go into here.*

* i.e. They are governed by the needs of the plot.