A concrete noun is a word that refers to something tangible, something that can be perceived through the senses. For example, "book", "table", and "tree" are all concrete nouns. An abstract noun, on the other hand, is a word that refers to something intangible, something that cannot be perceived through the senses. For example, "love", "anger", and "peace" are all abstract nouns.
Music is an abstract noun because it is something that cannot be perceived through the senses. We can hear music, but we cannot see it or touch it. Music is a product of the imagination and exists only in the minds of those who create and experience it.