Let’s start with some translations:
Shavua = week (שבוע)
Tov = good (טוב)
Shavua Tov = have a good week (טוב שבוע)
Shavuot = weeks (plural) (שבועות)
Shavuot is then the Festival of Weeks, and it is called that because it ends the seven weeks of the Counting of the Omer, or more specifically, the seven weeks between Pesach and the celebration of Shavuot itself. So, Shavuot has a double significance in that we celebrate the wheat harvest in Israel and the giving of the Torah to the Israelite people at Mount Sinai, a most important occasion in Judaism.
This festival begins at sundown on the 5th of the Hebrew month of Sivan (5 Sivan) and depending on your Jewish affiliation, this holiday lasts one or two days in the Diaspora (Diaspora means anywhere outside of Israel), but only one day inside the Land of Israel. This holiday is one of three Jewish Festivals mentioned in the Torah, the other two being Pesach and Sukkot, where all Jews used to have pilgrimages to the Temple in Jerusalem to celebrate and bring their offerings; in this particular holiday, the first fruits of the season. In the Gregorian calendar, this Festival falls at the end of May or beginning of June, depending on the year.
Today, there are many ways to celebrate this holiday:
1. No work is done. It is a day of Holy rest.
2. Light up the candles to welcome the Holiday
3. Eat foods containing dairy. Some favorites are cheesecake, blintzes, kreplach, and pastel de siete cielos.
4. It is customary to spend all night learning Torah
5. Read The Book of Ruth (a convert to Judaism herself)
6. Decorate your surroundings with greenery (flowers, plants, etc).
7. Go to synagogue and listen to the 10 Commandments
The giving of the Torah by G-d to Moses is celebrated grandly on Shavuot. We remember that Passover, or Pesach, was the time the Israelites left Egypt. It took them seven weeks to reach Mt. Sinai, and thus, receiving the Torah by the hand of G-d, a momentous occasion; one we celebrate to this day, during this holiday, seven weeks after Passover.