Pole dance transitions are just that...moves that link one trick, spin, climb or move to another. Transitions such as a pirouette, backslide orsexy floorwork help link all of the moves together in your routine.
These various moves are not difficult to learn and look really good when using them. It does not look good for a pole dancer to just move from one trick to the next, standing and wiping her sweaty hands or looking up at the pole instead of using a move to flow into the next trick.
Transitions can be slow or fast. Here is a video clip where the routine uses some pole overs, pirouettes and hip grinds in between the spins:
Here are a few video clips with moves that will come naturally once you learn them and start using them while you are working out on your pole. Start to incorporate one move at a time until it feels second nature when you are practicing on your pole.
All of these moves help link one pole dance move such as a spin or climb together. There are other transitions that are specific to aerial tricks. Check out these pole dancing move guides that will help you learn the names of tricks and how to perform them.