When musicians see the phrase meno mosso in a piece they’re playing or singing, they know they need to reduce the speed, giving the music a sense of less motion and a more relaxed vibe.
Meno mosso literally means "less motion" in Italian, but in terms of actual performance, what that translates into is mainly less speed. Playing your instrument more slowly does require less vigorous physical motion from your hands, but it also makes the music itself feel more restful and relaxed, like someone walking instead of running.