"This person has a blue watch."
Translation:Αυτός ο άνθρωπος έχει ένα μπλε ρολόι.
Not necessarily, but it's an accepted answer. In Greek, it's common to use άνθρωπος in place of άτομο=person.
«ο» in sentences is not pronounced «omikron» but «ο» An example here: Ο άντρας είναι καλός(prn. The man is good), but we don't say: Όμικρον ο άντρας είναι καλός(prn. Omikron man is good)
You’re supposed to translate the entire sentence, not just a single word.
What was your entire answer?
There are accepted alternatives that include the word άτομο.
Αυτός ο άτομο έχει ένα μπλε ρολόι was marked incorrect for using the wrong word and άνθρωπος was suggested as the acceptable answer
I thought it might be something like that, but of course it’s impossible to guess correctly.
άτομο, like just about all nouns ending in -ο, is neuter, not masculine.
Thus “this person” is αυτό το άτομο, not αυτός ο άτομο(ς).
If the noun and the gender of the words before it don’t match, Duo can’t tell whether you used the wrong noun or the wrong gender of other words. It generally guesses that the first word (e.g. the article) is correct and the second word (e.g. the noun) is wrong.
Things like this are why you should always quote the entire sentence, because the error is often not where you think it is, but in some other word.
Oh yes! I see now - I hadn’t considered that. Thank you for your help and clarification.