It is also the yarhtzeit of Rabbi Shimon Bar Yochai, the author of the Zohar, the Kabbalah, the book of Jewish Mysticism. Tradition has it that the day of his demise was filled with a great light of endless joy through the secret wisdom which he revealed to his students in the Zohar. In Israel there are huge bonfires across the country. From Pesach onwards the children gather fallen branches and old tires and build pyres often 20 and 30 feet high. Haircuts and weddings take place on this date and there is much festivity including dancing, singing and music.
Every Hebrew letter has a numerical value.
So L'ag B'Omer means the 33rd day of the Omer. The portion ends with the interesting story of a man who blasphemed G-d's name with a curse. The Israelites were redeemed from Egypt in order to accept the Torah at Sinai and to fulfill it. The counting of the days from the exodus from Egypt until the day of the accepting of the Torah is an expression of the importance of the Torah for the Jewish People. Just as a person who is enslaved and knows that he will be liberated on a certain day will count each day until he finally gets his freedom, so too, we count the days until we receive the Torah.