1.
the 5th of the month
Used to refer to the fifth day of a calendar month.
五日 uses the native Japanese counting series for days 1–10 of the month: 一日, 二日, 三日, 四日, 五日, 六日, 七日, 八日, 九日, 十日. The same forms also count durations in days (except 一日 for 'one day' as a duration).
Disambiguation
Do not confuse with いつか (someday, sometime), which is written either in kana only or with kanji 何時か. The two are unrelated despite the identical reading.