Non-PRO Hindi to English Art/Literary Poetry & Literature

“The priest has said the balli must be done at amavas, darkest no-moon night of the month. You must sacrifice a chicken.”

the situation is as follows: the man's wife died years ago because she fell from a tree. they had a son, and some time after the accident, he saw his mother's ghost (angry because she died a violent death) trying to get hold of him. so in order to save the son from the angry ghost, the priests tell the family as quoted above.

the quotation itself seems to explain amavas: the darkest night of the month. and i vaguely assume "balli" must be a sacrifice, but can you please explain for sure what exactly "balli" means. thank you.