Can mean different things depending upon context. Did you have a specific context this was used in?
Dynamic Space could be referring to spaces that can be changed to suit different needs and events.
Dynamic Space could refer to space that changes over time, for instance a square which is shaped by the various markets and other events that happen within it.
Dynamic Space could refer to a physically changing space, for instance park spaces used to contain flooding waters, that change as teh seasons and weather changes.
Dynamic Space can also be used to simply refer to space that tend to influence the activities of the people using that space, for instance a well designed passageway which directs pedestrians and provokes them to explore around the corner.
And Dynamic Space can be a design element, a certain "thrust" to the layout, which makes the place more exciting.