Rosh Hashanah is the Jewish New Year and translates from Hebrew to mean, literally, "the head of the year". This year, the two-day celebration begins Monday, September 6 and ends at sunset September 8[1].
The holiday marks the beginning of the High Holidays, leading up to Yom Kippur, a solemn day of atonement and the most sacred day of the year for Jewish people.
For Rosh Hashanah, those who celebrate often attend synagogue, eat foods such as apples and honey - which is meant to usher in a sweet new year - and pray. Another Rosh Hashanah tradition is the blowing of the shofar - a rams horn, which serves as a call to repentance.
This year, the Jewish year is 5782. The Jewish calendar is based in the teachings of the Torah[2].
L'shana Tova to all who celebrate!
1) https://www.usatoday.com/story/news/nation/2021/09/02/rosh-hashanah-2021-dates-what-know-jewish-holiday/5669527001/
2) https://www.myjewishlearning.com/article/counting-the-years/