identify the significance of sacrifices in african religious worship?

Question

to explain how, why and when africans offered sacrifice as a form of worship

Answer 1

... you want generalizations of the beliefs and practices of a CONTINENT of people, without specifying even a time period?

Almost any answer that can be made to the question as stated will be misleading and useless.

Can you narrow down the question a bit?

Answer 2

To my knowledge, no one knows exactly when African sacrifices began, as apparently they have been going on for centuries.

The significance of an African sacrifice, is that what ever was offered had value to the person making the sacrifice, and therefore he was offering something that he either needed or wanted. He chose to deny himself this luxury.