Final answer:
Pentecost is a religious holiday celebrated fifty days after Easter, commemorating the descent of the Holy Spirit on the Apostles and the beginning of the spread of the Christian faith.
Step-by-step explanation:
Pentecost is a religious holiday celebrated fifty days after Easter, which commemorates the descent of the Holy Spirit on the Apostles. In the biblical account, the Holy Spirit appeared as tongues of fire and inspired the Apostles to preach about Jesus in different languages. It is a significant event in Christianity as it marks the beginning of the spread of the Christian faith.