All holidays begin at sundown on the evening before the date specified in the calendar. For example, if the dates for Rosh Hashana were listed as Sep 19-20, then the holiday begins at sundown on Sep 18 and ends at sundown on Sep 20. Dates in bold are yom tov, so they have similar obligations and restrictions to Shabbat in the sense that normal “work” is forbidden.
This information is provided by HebCal.com
Get the Calendar
The 5 Year Holiday Calendar can be accessed by clicking below. The tables of holidays include the current year and 4 years into the future for the Diaspora.