What does someone speak in the spirit when no man understands him?

According to 1 Corinthians 14:2, the one speaking in a tongue speaks not to men but to God, and no man understands him. In the spirit he speaks secrets—things not everyone can understand, truths previously kept secret in the mind of God.

Les explains that the word "unknown" in 1 Corinthians 14:2 is added by the translators, and he prefers to leave it out. The verse says that he who speaks in a tongue speaks not unto men but unto God, for no man understands him. Yet in the spirit he speaks secrets—things not everybody can understand, those things that were kept secret in the mind of God.

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.

Why does Paul say the one speaking in an unknown tongue speaks to God and not to men?

Paul says the one speaking in an unknown tongue speaks to God and not to men because no man understands him; God alone could make anything out of it if possible. The speaker, in his own human spirit, speaks mysteries, not communication that men can decipher.