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 birth is necessary to enter the kingdom of God.

"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 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. ... 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 3:5, 8 KJV