Shauvot, the Feast of weeks (Pentecost)

 celebrating the provision from God to meet our physical needs, a wondrous act of God 's grace
Celebrating supernatural revelation, the giving of God's word. 50 days after passover, Moses was called to go to the top of the mountain to receive the Torah, the revelation of God's will, God's love and God's character.
Celebrating the outpouring of the Holy spirit. As the fire came down on Mt Sinai, the fire of His glory now came down upon the disciples, equipping them to with His power to see the sick healed, the oppressed delivered, the Gospel boldly proclaimed, and the world changed. 

Exodus 19 v16-20
Acts 2v1-4 , while celebrating shavuot ( 50 days after celebrating Passover ), the Holy Spirit filled the disciples and Peter preaches to the crowd, those who believed what he said on that day were about 3000, God's grace as He replaces those killed after the golden calf incident ( about 3000 died that day - Exodus 32 v 28 )