Can be used for both males and females, but the feminine form is 'rubia'.
Ella tiene el cabello rubio y siempre lleva una sonrisa que ilumina el lugar.
She has blond hair and always wears a smile that lights up the place.
Su pelo rubio brillaba bajo la luz del sol, atrayendo miradas de admiración.
Her blond hair shone under the sunlight, attracting admiring glances.