Translation:The seventh day of February is the holiday.
I agree with Gerald that "on" would be the problem. There is no ON (ma or i) in the Hawaiian sentence. If the Hawaiian sentence had ON (ma or i) it would probably start with (Aia).
With the Hawaiian word construction with (ʻO), the sentence can be translated as
"The holiday (is) February seventh. or February seventh (is) the holiday."
Did you lead with "The holiday is..." or "The seventh day is..."? To me, it looks like [the seventh day] is the subject, and [the holiday] is the object. For the English translation, the subject should lead. [The seventh day] [of February] [is] [the holiday]. But, like Gerald said, sometimes DL makes a switch.
agree - now that I look at my (incorrect) answer more closely ("The 7th of February is a holiday") I can't tell if my error was leaving out "day" or using "a" instead of "the" (or maybe both?) because nothing was underlined in the correct answer. (But it made me think, anyway! ;) )