The single festival of Shavuot has several names and the meanings of each is crucial to the understanding of the significance of this particular festival.
SHAVUOT - "And you shall observe the Feast of Weeks, of the first fruits of wheat harvest." (Exodus 34:22)The "Festival of Weeks." The Passover-to-Shavuot countdown. The name reflects the fact that this holiday occurs seven complete weeks (shavuot) after Passover.
THE FESTIVAL OF THE FIRST FRUITS (Chag Habikurim) - The natural cycle that has been completed is agricultural. On Chag Ha'Bikurim, the offering of the First Fruit of the harvest ,wheat, barley, grapes, figs, pomegranates, olives, and dates were brought to the Holy Temple in Jerusalem as a gesture of thanksgiving for the successful yield.
"A land of wheat and barley, and vines and fig-trees and pomegranates; a land of olive-trees and honey" (Deuteronomy 8:8)
ATZERET (Conclusion) - It refers to the end of the period that began with Passover, as if bringing to a close the seven week long holiday.
THE FESTIVAL OF HARVEST (Chag HaKatzir) -
"And the festival of harvest, the first fruits of your labors, which you sow in the field" (Exodus 23:16). Originally Shavuot was an agricultural festival.On Shavuot the sample of the first crop of the wheat harvest was brought to the Temple,baked into two loaves of leavened
bread, and then waved before the altar as the concluding rite of the season.
THE TIME OF THE GIVING OF TORAH (Zman Matan Torah) -
According to rabbinic interpretation, the Ten Commandments were given to the Jewish People on Mount Sinai on the sixth day of Sivan. Thus, in addition to being a thanksgiving for the wheat harvest, Shavuot has also became a celebration of the Torah. Shavuot commemorates the giving of the Torah to the Jewish People. The Festival prayer "The day of the Festival of Shavuot, the time of the giving of our Torah, a holy convocation" is recited by the Jewish people.