Origin: English, Old Norse
Meaning: it could be a feminine form of Dune, an English word referring to a sand hill formed by the wind in deserts or near coastal regions; the word itself comes from Middle Dutch dūne, which itself could possibly be derived from Gaulish dunum (hill) or from Proto-Celtic dunom (stronghold, rampart).
Duna is also the Italian and Spanish word for dune.
Duna is also an Icelandic feminine name, a variant of Dúnna which is the feminine form of Dúnn from Old Norse meaning "eider-down", the name of a duck.
It's also the Hungarian name for the Danube river running through Central and Eastern Europe.