This picture shows some Indian women celebrating Diwali - the most important festival of the Hindu calendar.
Diwali is marked with joyous celebrations on 17 October. It is symbolic of the triumph of good over evil. Here is how Wikipedia explains its origin:
In Hinduism, it is the homecoming of Rama after a 14-year exile in the forest and his victory over Ravana. In the legend, the people of Ayodhya (the capital of his kingdom) welcomed Rama by lighting rows (avali) of lamps (dĭpa), thus its name, dīpāwali.
And of course that is why the day is referred to as "the Festival of Lights".