Original: Rosh Hashanah is the first of the High Holidays or  ("Days of Awe"), or  (The Ten Days of Repentance) which are days specifically set aside to focus on repentance that conclude with the holiday of Yom Kippur.
Simplified: Rosh Hashanah is the first of the High Holidays or Yamim Noraim, or Asseret Yemei Teshuva (The Ten Days of Repentance) which are days specifically set aside to focus on repentance that conclude with the holiday of Yom Kippur.