Multiverse is the name given to the theoretical space outside of the universe. The space within the universe consists of three spacial dimensions (length, width, and depth) and one temporal dimension (linear time) together with other dimensions that we can’t perceive. Hyperspace consists of all of these dimensions and at least one more spacial one, and may in fact incorporate all twelve dimensions.
Within the multiverse, universes drift near and around each other, similarly to how galaxies drift around each other in normal space. There are different theories as to how these different universes can interact. Some models predict that universes attract one another gravitationally, and that universal collisions cause a Big Bang in each universe. Others predict that universes reproduce here by budding off of their parents, making hyperspace something of a cosmological nursery. Still other theories combine the two ideas.
It is unclear precisely how time flows in hyperspace. If linear time exists there, then events flow from cause to effect, as in this universe. However, it is possible that hyperspace incorporates "curved time", where cause and effect are not always progressive and events can repeat themselves, or occur simultaneously as wholly different events, or even flow backward. It is also possible that time flows in another manner altogether, inconceivable to humans living in this reality. Indeed, it is even possible that, in the multiverse, time doesn't exist at all. 
Christian Fundamentalists rarely have any reason to even consider subject matter like this, but the reactions of those who do are often ones of rabid denouncement. They tend to laugh at the idea of a multiverse and cite the unlikelyhood of such an existence. The irony of this is, of course, palpable, as they put stock in something without a shred of evidence for it (God). At least hyperspace can be expressed in terms of mathematics. And indeed, if God exists outside of our observable reality (a favorite claim of fundamentalists), hyperspace would need to exist for him to dwell in- otherwise, a paradox occurs by which God neither inhabits the universe nor exists outside of it, a phenomenon that could not be unless God were not real. (Liberal Christians are often willing to accept this viewpoint with little trouble.)