What is the primary site for absorption of nutrients?
In the small intestine. Villi are small finger like things that cover the inside of the small intestine and absorb most of the nutrients you consume.
If your asking about primary absorption in digestion and the absorption of nutrients into the body, then primary absorption is the first (primary) place in the body where nutrients are absorbed. In humans this takes place in the small intestines after the food has been broken down in the stomach and passed on to the small intestine.