"The house has two floors."
Translation:La domo havas du etaĝojn.
"story, stories" and "storey, storeys" are both correct spellings for the floor of a building. (And even, it seems, "storey, stories".)
"Storey" is apparently a predominantly British form, so I suppose Duolingo (which theoretically uses US English as its base) should show "story" if it shows this word at all, but accept either spelling.
new word for me .. "etagxo" can someone expand the explanation of this for me ^_^ thanks