The red circle on her forhead is called a 'bindi' in Hindi, and 'Pottu' in Malayalam.
You may also notice a light yellow horizontal mark above the pottu. This is called as a 'kuri' in Malayalam, and its actually sandalwood paste. Its typical of South Indian girls to wear a kuri, usually after bath. Temples in Kerala, and other parts of south India offer a tiny amount of saffron paste to devotees as blessings from God.
