We like using less simple terms when we are revealing things of an esoteric nature. Some people are basically not supposed to understand revelations!
So "plurality" in the heading simply can be transalted to "the state of tennis coaching" ( state - the way something is with respect to its main attributes).
For example, we have all heard tennis-trainers shouting instructions to a trainee during live-ball rallying: this has many aspects / "pluralities" as a teaching technique. For instance it my be overwhelming for students who may balk at the instruction, as they are focused on ball; or it may freeze another trainee into inaction in trying to understand and onboard instruction; and verbal cue maybe understood and executed by quick-witted hearing-actioning bain player etcetra.
So tennis-coaching instructons and how delivered comes down to that age-old science known as communication, or as i would like to say empathically "effective comms".