Girl
Young Girl
noun
A little woman is a girl.
少女 is a relatively formal word that's often used in writing to describe a young girl, usually between childhood and adolescence (or between the ages of about five and eighteen).
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
三人の少女が川にいた。
Three girls were at the river.
おすすめの本のジャンルは、少女マンガです。
The book genre I recommend is girl's manga.
少女のようなスマイルの四十才だ。
She's a forty-year-old with a smile like a young a girl.