KJV:
But ye shall receive power, after that the Holy Ghost is come upon you: and ye shall be witnesses unto me both in Jerusalem, and in all Judaea, and in Samaria, and unto the uttermost part of the earth.
NKJV:
But you shall receive power when the Holy Spirit has come upon you; and you shall be witnesses to Me in Jerusalem, and in all Judea and Samaria, and to the end of the earth.
NIV:
But you will receive power when the Holy Spirit comes on you; and you will be my witnesses in Jerusalem, and in all Judea and Samaria, and to the ends of the earth.
Interpretation:
Jesus promises His disciples that they will receive power when the Holy Spirit comes upon them. They will be witnesses to Jesus throughout the world. The verse shows that the Holy Spirit gives power for witness. We cannot serve God effectively without the Spirit's power. The verse teaches that God's power enables us to witness. Those who receive the Holy Spirit receive power from God. The verse reminds us that God's power works through us to reach others.