Pentecost is the day of Holy Spirit. Holy Spirit is Comforter, Counselor, and Teacher of Jesus' words.
Jesus teaches of Holy Spirit in John 14.26 But the Advocate, the Holy Spirit, whom the Father will send in my name, will teach you all things and will remind you of everything I have said to you.
It is fulfilled in Acts 2.1 When the day of Pentecost came, they were all together in one place. 2 Suddenly a sound like the blowing of a violent wind came from heaven and filled the whole house where they were sitting. 3 They saw what seemed to be tongues of fire that separated and came to rest on each of them. 4 All of them were filled with the Holy Spirit and began to speak in other tongues as the Spirit enabled them.
Holy Spirit is also intercessor. Romans 8:2626 In the same way, the Spirit helps us in our weakness. We do not know what we ought to pray for, but the Spirit himself intercedes for us through wordless groans.
The new era of grace has already arrived here. Holy Spirit will come and rest in us together. Now anyone who calls the name of the Lord will be saved. Holy Spirit is here with us all the time, to teach us, remind us, and comfort and encourage us. We should be the one who goes on for the kingdom of God by relying on the power of the Holy Spirit.