Original Post. The sentence in my book reads:
ひようびは あかいひです。
This means Kayobi wa Akai hi desu.火曜日は赤い日です。 (かようびはあかいひです)。
Tuesday is a public holiday.
But on its own doesn't make any logical sense . However when looking at the calender and saying "Kayoubi wa Akai hi desu" Then it is understandable.
Hiyoubi is read as Kayoubi Tuesday. Akai hi is because on Japanese calenders public holidays are in red.
Cheers