In KiCad, a hierarchical sheet can be drawn once, and then included multiple times in the project. An example for this would be an USB hub. You can make a hierarchical sheet for an USB output connector and it’s surrounding protection circuitry, and then each output of the USB hub will get that circuitry around it’s connector.
For more info about Hierarchical sheets:
Related to this there is also a “Replicate Layout” script.
With this script you do the layout of one instance of a Hierarchical sheet on the PCB, and you also place a single reference Footprint for all the other sheets on the PCB, and then run the script, and it takes the layout (Tracks and Footprints) of the Hierarchical sheet you designed on the PCB and it replicates that layout for all the other instances of the Hierarchical sheet. This script can also be run multiple times when making revisions of a project.
I don’t know what that “AR” thing is, but I guess it has something to with managing the RefDes to make this multi inclusion of a Hierarchical sheet possible.