Translation:Is it two o'clock?
か is a particle like は and が. English doesn't have particles so there's no direct translation, but it's like a verbal question mark.
I love the way you described it, it helped me too, since i had the same question. (:
Yes, か is a particle to indicate questions. It's actually used instead of the question mark. So this sentence could be made without the questiin mark and still be a question
You specify AM or PM by using ごぜん(AM) or ごご(PM) before the time: "何時ですか？", "ごぜん４時です。"
She does say it pretty distinctly unless it was changed since you heard it.
I said ,,It is..." instead of ,,Is it..." and said is wrong. Was it? Or it's a mistake from the app?
"It is two o'clock" is definitely wrong.
It is two o'clock.
Is it two o'clock?
Note how the か at the end of the sentence turns into a question. "It's two o'clock?" would technically be correct, but Duolingo's grading machine doesn't look at punctuation and so relies on word order.