On that day is "aujourd'hui" (for today) or "en ce jour" (for any day even in the past) in French.
'on this day' in french is 'ce jour-là'
Per day is 'par jour' in French.
you say "jour" for day
To say, "Will you go out with me one day?" in French you say: Sortirez-vous avec moi un jour ?
Jour
Canada Day in french is "La fête du Canada"
today was a good day in french
C'etait une longue journee means "it was a long day" in French
It is "du jour".
You say "nouveau jour"... nouveau = new / jour = day.
To say "have a good day" in French, you can say "bonne journée."
first day = premier jour