What does the Bible say about the role of the Holy Spirit in Pentecost?

At Pentecost, the Holy Spirit descended upon the apostles, fulfilling Joel's prophecy that God would pour out His Spirit upon all flesh. This event signified the inauguration of the last days, encompassing the entire period from Christ's first coming to His return. The Spirit empowered the apostles to preach boldly in various languages, illustrating God's sovereign purpose in gathering His elect from all nations. The natural man cannot comprehend spiritual truths, but the Spirit helps believers understand and proclaim the divine gospel.