It is the food of the gods. It literally means 'immortality'. The fruit of the tree can be pressed into magical wine (sacred nectar).
Cupid once interceded for his wife with Zeus because Venus was jealous that a mere mortal could compete with her beauty. The king of the gods decided that Psyche should become immortal. She was given a cup of ambrosia to drink and thus she became immortal.
Valanice's mother once told her daughter when she was small, about "nectar and ambrosia", nectar was sacred drink (from flowers), and that ambrosia was sacred food of the gods.
Some are allergic to ambrosia, it makes them sneeze.
Looking to be a strange substance a growht perhaps, growing above special trees, or rather growing from a certain type of tree, and smells delicious. The odd fruit breaks off in bunches, somewhat resembaling grapes . The fruit smells sweet and lovely. Valanice however never tried it as she wasn't sure if it was actually good to eat (this is probably a good thing), but rather she offered it to dragonettes who enjoyed and sang her a tune.
It's not clear if someone has to continually eat it to maintain immortality, if eating the berries alone once, or drinking concentrated nectar made from the fruit is enough give immortality. It is possible that eating unprocessed could heal wounds and sickness and confer a long healthy life, unless consumes in large quantities.
Behind the scenesEdit
In the ancient Greek myths, ambrosia (Greek: ἀμβροσία, "immortality") is sometimes the food or drink of the Greek gods, often depicted as conferring longevity or immortality upon whoever consumed it. It was brought to the gods in Olympus by doves, so it may have been thought of in the Homeric tradition as a kind of divine exhalation of the Earth.