When you receive the Holy Ghost, you speak in another tongue (language) as God speaks from within you. This is a language that you have not learned, but are words spoken “as the Spirit of God gives the utterance.”

"And they were all filled with the Holy Ghost, and began to speak with other tongues, as the Spirit gave them utterance." - Acts 2:4 KJV

Speaking in tongues is a universal sign that a person is being filled with God’s Spirit. It occurs when a person is being “born of the Spirit.” EVERYONE experiences speaking in tongues when they are born of the Spirit, and this is part of being born again (of water and of the Spirit) which is necessary to enter the kingdom of God.

"Jesus answered, Verily, verily, I say unto thee, Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God." - John 3:5 KJV

The Gentiles at Cornelius’ house spoke in tongues when they received the Spirit (the Holy Ghost).

"And they of the circumcision which believed were astonished, as many as came with Peter, because that on the Gentiles also was poured out the gift of the Holy Ghost. For they heard them speak with tongues, and magnify God." - Acts 10:45-46 KJV

Jesus told Nicodemus that there would be a sound when a person is born of the Spirit. Jesus compared the Spirit and the sound of being filled with the Spirit to the wind. You can’t see the wind but you can hear it.

"The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth: so is every one that is born of the Spirit." - John 3:8 KJV

On the Day of Pentecost, it is recorded that there came a sound AS of a rushing mighty wind. This sound turned out to be all the people in the upper room speaking in tongues as they were filled with the Holy Ghost (the Spirit).

"And when the day of Pentecost was fully come, they were all with one accord in one place. And suddenly there came a sound from heaven as of a rushing mighty wind, and it filled all the house where they were sitting. ... And they were all filled with the Holy Ghost, and began to speak with other tongues, as the Spirit gave them utterance." - Acts 2:1-2, 4 KJV