"The girl's pink dress."
Translation:Το ροζ φόρεμα του κοριτσιού.
I agree with navajos :) "Το φορεμα της κοριτσιου ειναι ροζ" is incorrect, only because the word "κοριτσι" is not feminine (weird, I know) but neuter. It should be "Το φορεμα του κοριτσιου ειναι ροζ" instead :).
Putting that aside, the sentence you wrote translates to "The girl's dress is pink", as opposed to "The girl's pink dress". Only a subtle difference, with a slight difference in meaning.
Very close though and keep up the good work! Greg.
Γεια σου Ελένη! There are typos and grammar errors in your sentence. Even without them, I reckon this is wrong, as you are using a verb -είναι- even though the English sentence doesn't have one. Yours is full with a concrete meaning, while the English one is more like a title or part of a full sentence. Hopefully this makes sense :)