一日（ついたち）— the first day of the month
一日 は 休み です。
The first is a day off.
一日ついたち
the first day of the month
ついたち
accent [4]In detail
Words
一日ichinichithe first day of the month
はwa(topic marker)
休みyasumiday off
ですdesu(polite sentence ending)
Kanji
一イチ・
日ニチ・
With the reading ついたち, 一日 means the first day of a month. Learn this calendar reading as a whole word. It does not mean “all day” here.
Coco-sensei