Think of an RPL as your basic pilot licence. You can build or buy your own helicopter and fly it without needing another pilot in the cockpit with you. It has a few limitations of course, you may only carry one passenger and you’re unable to travel further than 25 nautical miles from your take-off point. However, navigation and radio endorsements can be added to give you the option to fly further, and into controlled airspaces.
This licence is very useful for example if you need to survey large properties from above, or you’re interested in building your own kit helicopter to take out for a spin from time to time.