She has a long black hair and blue eyes.
She has long black hair and blue eyes.
Her hairs are curly and blonde.
Her hair is curly and blonde.
Hair is uncountable when it refers to all the hair on someone’s head. We do not use a, and we use a singular verb: ‘Her hair is very long.’
Hair is countable when it refers to one or more individual hairs: ‘There is a hair in my soup.’ ‘There are some hairs in the basin.’