"Now, Lord ... grant to Your servants that with all boldness they may speak Your word, by stretching out Your hand to heal, and that signs and wonders may be done through the name of Your holy Servant Jesus.
And when they had prayed, the place where they were assembled together was shaken; and they were all filled with the Holy Spirit, and they spoke the word of God with boldness."
Acts 4:29-31
Here we see the power of the Holy Spirit for preaching with boldness, healing and deliverance.
Signs and wonders include healing, casting out devils,giving sight to the blind, hearing to the deaf, making whole those who are crippled, raising the dead and other miracles.