Maybe it's a tale of a musician who stumbles into a ghostly realm and his singing somehow connects with the spirits. There could be elements of mystery and fantasy in it.
The cartoon guy might be singing incoherently because of some internal chaos or to create a unique and chaotic scene. Maybe it's part of the show's style to be unpredictable and odd.
I really don't know. It could be part of a creative idea for a children's story or a theme in a fantasy cartoon. But without specific details, it's all just speculation.