The Jewish Holidays in May 2025

Lag b'Omer is the 33rd day of the 49 for counting the omer (sheaves of barley) from Passover to Shavuoth.  It is a respite from the sadness of this 49-day period, which is a time of contemplation before receiving the Torah at Mt. Sinai and usually a time during which there are no celebrations.  It is also associated with a plague that killed 24,000 of Rabbi Akiva's students.  

However, on the 33rd day, none of Akiva's students died, so it became a day of celebration ("Lag" is 33, using the letters of the Hebrew alphabet as numbers).  Also, it is associated with the anniversary of the death of Rabbi Simon Bar Yochai, the author of the Zohar, the original book on Kabbalism (Jewish mysticism).  In Israel, bonfires are set in his memory.