"Avranno un'ora."

Translation: They will have one hour.

[Sjurstvold]

"They will have an hour" should be accepted :-(

[0qnJTezk]

I wrote "avranno un ora" which is exactly the answer they gave but was told I had a typo and "un ora" were each underlined.

[CivisRomanus]

Yes, un ora is mispelt, because an apostrophe is missing. The correct spelling is un'ora.

Without a context, this sentence can also translate as "They may have one hour" (conjectural use of the simple future).

[0qnJTezk]

They didn't give an apostrophe in the correction

[CivisRomanus]

You can report this as a mistake.