The_Creature

Different cultures have different musical traditions which often sound a bit like noise/nonsense to people from outside that culture (at least when they're first exposed to it). However, there are aspects of ordinary communication that are pretty universal across cultures that are reflected in music. For example, someone speaking slowly is likely to sound sad whereas fast speech is happier sounding (I know I'm simplifying quite a lot here). Arguably the same is true for the tempo of songs. I'm not allowed to post links but there are studies that show people are pretty good at recognising very basic emotions like happiness and sadness when listening to another culture's music.

I think when people talk about music being a universal language they mean it's better at expressing this more subtle level of communication that occurs alongside the actual content of what a person is trying to say; a level which has at least some claim to being universal.