This system comprises two parts, an indoor unit and an outdoor unit. The indoor unit is mounted to your wall (exterior walls are easier and therefore cheaper to install) and the outdoor unit is located as close as practically possible to the indoor unit.
If you are wanting to have air conditioning in more than one room, but cannot have Ducted Reverse Cycle, then the Multi Split Systems could be suitable to you. They comprise of a number of indoor units (one in each room) with only 1 outdoor unit. These are suitable for those places that may not have the roof space for a Ducted Reverse Cycle Unit or an office type environment where different temperatures are required for different rooms.