What holiday is celebrated at the end of the jewish year

30 Kislev - 1 Tevet December 8-9, 2018 Rosh Chodesh of Tevet

The last jewish holiday of the year is the Kislev/Tevet.

The Torah specifies a single date on the Jewish calendar for observance of holidays. Nevertheless, festivals of Biblical origin other than Shabbat and Yom Kippur are observed for two days outside the land of Israel, and Rosh Hashanah is observed for two days even inside the land of Israel.