There are a number of places in the New Testament that talk about speaking in tongues. As I understand it, speaking in tongues means the miracles of being able to speak in other languages that you have not learned naturally. For example, I only know how to speak English because I grew up in an English speaking country and I never learned any other language. But if I had the gift of tongues, I could speak Spanish with Spanish-speaking people, Russian with Russian-speaking people, etc. without having to study those languages. It would be a miracle from God. In other words, the gift of tongues is really the gift of languages.
To the best of my knowledge, no one today has that gift. I do not believe that what some Pentacostal groups call "speaking in tongues" where someone would speak nonsense syllables that no one including the speaker can understand is the same thing that the Bible calls tongues.
Here are some scriptures on the subject:
Acts chapter 2 and chapter 10
1 Corinthians chapters 12 thru 14
Revelation 7:9, 11:9, 17:5
Isaiah 66:18
As far as your friends are concerned, an important question is, do they try to live morally even if they do not have faith in God? I agree with those who say you should not try to force your faith in God on them if they don't want it. You can still be friends with them and obey your faith in God quietly. But if their moral standards are wrong, if they engage in immoral conduct, use vulgar language and speak God's name disrespectfully, lie, etc. you may want to put some emotional distance between them and you and seek out friends who live a moral life. Otherwise, your "friends" can drag you down. If they are immoral, and you are moral, you won't change them, they will change you.
I hope this helps.
