Tongues: see the comments on 1 Cor. 14.2.
Even more (Good News Bible‘s “rather”) is the usual meaning of the Greek word translated “especially” in verse 1. A contrast is implied here: although Paul would like all believers to speak in tongues, he feels that the gift of prophecy is a more important one and should be desired. The first sentence of this verse may be rendered as “I would like for all of you to speak with strange sounds; but more than that, I would like you to have the gift of proclaiming God’s message.”
To prophesy may be rendered as “to proclaim a message from God.”
Greater is the word translated “more excellent” in 12.31. Good News Bible is right to expand it to “of greater value,” since Paul is not at present concerned with the importance of individuals in themselves, but with the value of their contributions to the Christian community. One can render this phrase as “has more importance” or “has greater usefulness.”
The phrase unless some one interprets is literally “unless he (or she) interprets,” and that is how New International Version and Revised English Bible translate. As Fee points out, this does not contradict 12.30 or 14.28, since Paul nowhere says that the Christian may have only one spiritual gift; for example, speaking in strange tongues or explaining what is said in them. However, He who prophesies is another generic singular, meaning “anyone who prophesies.” Paul is probably thinking of a group of people who between them have both gifts, so some one is an adequate translation. Compare New Jerusalem Bible “… those who prophesy are of greater importance than those who speak in tongues, unless they can interpret what they say….”
In many languages it will be helpful to add “what he says” (Good News Bible) after interprets: “interprets what he says.”
Quoted with permission from Ellingworth, Paul and Hatton, Howard A. A Handbook on Paul’s First Letter to the Corinthians, 2nd edition. (UBS Handbook Series). New York: UBS, 1985/1994. For this and other handbooks for translators see here .