While British English maintains the French masculine–feminine distinction with the adjectives blond (for men) and blonde (for women), American English has largely adopted blond for both men and women, though blonde may still appear as the feminine adjective. Prefer The blond woman has a blond brother in American English and The blonde woman has a blond brother in British English. For anything non-human, use blond: The blond dog dipped under the blond wooden stool.
Do not use blonde as a noun, a lingering sexist synecdoche for blonde-haired woman. Prefer Do you see the woman? or Do you see the blond(e)-haired woman? to Do you see the blonde?