The holiday of Shavuot marks the giving of the Torah to Moses on Mount Sinai. It is also called the "Festival of Weeks" or "Pentecost." It's one of three pilgrimage festivals on which Jews from all over gather together in Jerusalem.
Shavuot marks a time when Jews celebrate and commemorate how God gave them His Holy Law (Torah). The Torah includes the books of Leviticus, Numbers, and Deuteronomy. According to tradition, God chose Moses as mediator for this giving because he was humble enough not to ask why he was chosen among his brothers to become the leader of Israel.
Today Jews celebrate Shavuot in memory of the giving of the Torah. They do this by reciting all or part of the 5 books of Moses called Torah at special services; they also keep a 24-hour fast and read from a book with prayers, songs, and poems. To remember how God gave them His Holy Law, Jews study Torah during the seven weeks before Pentecost.
The holiday is also known as "Zeman Herutenu", or "The Season of Our Freedom". The word "Zeman" means time or season. It is also called the Festival of Weeks because it falls halfway between Passover and Sukkot (Feast of Tabernacles).
It is one of three pilgrimage festivals during which Jews from all over gather together in Jerusalem. In ancient times, Israelites traveled to Jerusalem to offer sacrifices and worship God. Today, Jews still gather on this holiday to offer prayers and sacrifice; some also go there to visit the Western Wall and other holy places.
Shavuot means "weeks", because it falls seven weeks after Passover (which is called Chag HaMatzot). The holiday was also called "Pentecost", which means 50 days (not because it's 50 days long but because it marks the fiftieth day after Passover).