Shavuot is the most discreet holiday in the trilogy of Jewish holidays. Without a specific date mentioned in the Torah, it is celebrated fifty days after Passover. Unlike other holidays, it does not involve any specific mitzvah. The mitzvah proper to this day is that of bringing two loaves of bread to the Temple, an obligation incumbent on the community.
We will now try to understand the deep meaning of this holiday.
Each of the three major Jewish holidays has both a spiritual aspect and a close connection to the Temple and the Land of Israel. On Passover, marking our exit from Egypt, we are required to bring the Omer offering to the Temple. This offering, composed of barley, a food intended for animals, symbolizes the lower spiritual level of the people of Israel during their exit from Egypt, while they were still without Torah or Mitzvot.
Then the children of Israel undertook a fifty-day process of purification, preparing themselves to receive the Torah. This period, known as the โCounting of the Omer,โ represents this spiritual rise. Shavuot, celebrated at the end of this fifty-day countdown, marks the culmination of this period of purification initiated at Passover.
On the fiftieth day, the Torah commands the Jewish people to bring to the Temple an offering from the new harvest of wheat, which has fermented (chametz). Unlike almost all other offerings at the Temple, which were either flour or matzah (unleavened bread), this offering expresses the shift from animal food to food intended for human consumption. We can now consume leaven, which is strictly prohibited on Passover. Thus, the brandishing of these two loaves of bread in the Temple symbolizes the spiritual level reached by the children of Israel after this purification process.
(Torah excerpt from Rabbi Makover )