Speaking in tongues simply means speaking a language that connects u spiritually to god.The Bible explains this clearly in the book of Acts when the apostles of Christ, who were Galileans, spoke their own language and the audience heard it in their own native language. That shows that the miracle of the holy spirit is working. Speaking in tongues is not a useless sound or an invented language. It's a real languages like Filipino, American English or other dialects understood by people of different society Today, many group of people claim to speak in tongues but speak words that do not exist even in any language. Biblical speaking in tongues was a communication between man and God not a random noise.so speaking in tongues genuinely involves actual languages understood by other people.