Is balcony a abstract noun

No, the noun 'balcony' is a concrete noun, a Word for a type of structure that is part of the outside of a building or an overlooking structure within a building; a Word for a physical thing.

Abstract nouns are Word for things that your five senses cannot detect. You can't see them, hear them, smell them, taste them, or touch them. They are Words for things that you know, learn, think, understand, or feel emotionally.