Miko 巫女 is a priestess in a jinja, a Shinto shrine. She has a specific role and tasks in the daily life of a shrine. Among other things, she can perform kagura, the sacred dance.
Miko wears a pair of red hakama, white haori, and white and/or red hair ribbons.
White symbolizes purity in Shintoism.
The kanji 巫 means "medium, foreteller" and 女 means "woman."