changing calendar language

I created a reservation request form in which I have a date field with a calendar view. The terms "days" "months" "years" "hours" "minutes" are translated into French but before the time there's "at" which should be "à" in french and when I click on the calendar to choose dates, this one is in English. how to change the calendar language. 

Unfortunately, it's not possible to change the texts of the regular date picker.

However, you can use our localized calendar widget to show a calendar on a different language. Please check it out and let us know if it helps.