Shavuot is not explicitly named as the day on which the Torah was revealed by God to the Israelite nation at Mount Sinai in the Bible, although this is commonly quoted to be its main significance.
What is textually connected in the Bible to the Feast of Shavuot is the season of the grain harvest, specifically of the wheat, in the Land of Israel. In ancient times, the grain harvest lasted seven weeks and was a season of gladness. It began with the harvesting of the barley during Passover and ended with the harvesting of the wheat at Shavuot. Shavuot was thus the concluding festival of the grain harvest, just as the eighth day of Sukkot (Tabernacles) was the concluding festival of the fruit harvest. During the existence of the Temple in Jerusalem, an offering of two loaves of bread from the wheat harvest was made on Shavuot.
and the Feast of the Harvest, of the first fruits of your work, of what you sow in the field (i.e. Shavuot) ; and the Feast of Ingathering (i.e. Sukkot) at the end of the year, when you gather in the results of your work from the field.
On the day of the first fruits, your Feast of Weeks (i.e. Shavuot), when you bring an offering of new grain to the LORD, you shall observe a sacred occasion: you shall not work at your occupations.
You have magnified that nation, Have given it great joy; They have rejoiced before You As they rejoice at Harvest time (i.e. Shavuot), As they exult When dividing spoil.
(9) You shall count off seven weeks; start to count the seven weeks when the sickle is first put to the standing grain. (10) Then you shall observe the Feast of Weeks (i.e. Shavuot) for the LORD your God, offering your freewill contribution according as the LORD your God has blessed you.