Is this the same as "Manna from Heaven"?
No. Spelled with one "n", as in mana (and as in the title and subject of this movie), it is a Polynesian word referring to the spiritual force that accumulates in precious or powerful objects, people, or places. From Hawaii to New Zealand, Polynesians attributed mana not only to their greatest leaders, their holiest religious objects, their biggest trees and their sacred burial grounds, but (in lesser degrees) to everything in their environment.
Spelled with two "n"'s, as in manna (and in Exodus 16:31 in the Bible), it is of ancient Aramaic or Hebrew origin and is the substance which kept the Israelites alive in the wilderness during their escape from Egypt. Considered miraculous by many, it is sometimes identified today as either the sweet dried sap of a Mediterranean ash tree Fraxinus ornus, the lichen Lecanora esculenta (which is still sometimes made into bread), the lumpy sap from certain kinds of legumes native to Egypt and Syria, or the result of a scale insect (Coccus manniparus) puncturing the bark of a tamarisk tree (Tamarix mannifera), which causes the tree to drip sweet sap which falls on the ground and hardens. All of them are edible and can keep you alive in a desert wilderness for a while, but they aren't what this movie is about.