§ 02 · King James Bible
1 Corinthians 14:2
For he that speaketh in an unknown tongue speaketh not unto men, but unto God: for no man understandeth him; howbeit in the spirit he speaketh mysteries.
Simple English
When someone speaks in a language that others don't understand, they are talking to God and not to people. This is because nobody can comprehend what they're saying, but it's still a way of sharing deep secrets through spiritual communication.
* Work in progress - there may be occasional inaccuracies