Pacenotes are the shorthand language used by rally teams to navigate unfamiliar stretches of road at high speed.
These notes are made by the team before the race, when they are allowed two passes down the road: the first to create their own personal pace notes, and the second to check those notes and make any edits they'd like before the race. How well you make these pacenotes and how well you can listen to them and understand them at speed will have a direct impact on how well you can expect to do in the rally.
These skills take a lot of time (and/or dedicated training with an expert) to master. One of the easiest and most fun ways to practice making pacenotes and driving while listening to those pacenotes is to use a simple voice recording app on your smartphone. This will allow you to drive at normal speeds down any road in the world and dictate your pacenotes for that road, then go back and drive the road again listening to the pacenotes you've just made.
There are many potential uses for this system and exercises that you could do, in this video we simply practice a basic recce (reconnaisance) exercise which involves one pass of making notes and one pass of adjusting and editing those notes. You could then do a third pass and make clean notes, which could theoretically be used at high speed.
You could use this system to record one road or many roads, theoretically you could run your own rally with stages and transits (obeying all posted speed limits of course).