The B’nai Yisaschar, a chasidic work on the holidays,
writes that the numerology of the 49 days of the Omer is contained in the
phrase, "Lev Tov" a good heart, which is essence of the Torah.
The first 32 (=lev, heart) days of the Omer we try to develop a good
heart. Lag (=33) Ba’Omer represents the beginning of Tov=good. What is
good? The light of creation and of Torah. Lag Ba’Omer is the start of
the revelation of the light of the Torah which will be fully revealed at
the end of the 49 days, on Shavuos, when we receive the Torah.