"What then shall we say, brothers? When you come together, everyone has a hymn, or a word of instruction, a revelation, a tongue or an interpretation. All of these must be done for strengthening of the church." NIV translation
Paul now speaks of the necessity of allowing the gifts of God to be put to use in the church meetings. Once again, he reminds them and us that the purpose is for building up the believers.
"If anyone speaks in a tongue, two - or at the most three - should speak, one at a time, and someone must interpret. If there is no interpreter, the speaker should keep quiet in the church and speak to himself and God." NIV translation
Keeping in mind that the tongues (languages) are to be used to teach others, Paul gives some guidelines for their use in meetings of believers. If the speaker cannot be understood, he or she is to keep quiet. I have been to some meetings of believers where this is ignored. The congregation will make all kinds of strange noises on cue because they have been told that, if they do not do so, they do not have the Holy Spirit and so are not saved. This is a lie from the devil and is used to divide the people of God.
"Two or three prophets should speak, and the others should weigh carefully what is said. And if a revelation comes to someone who is sitting down, the first speaker should stop. For you can all prophesy in turn so that everyone may be instructed and encouraged. The spirits of prophets are subject to the control of prophets. For God is not a God of disorder but of peace." NIV translation
Now, Paul shifts his focus from the messenger and the subject of tongues to the message as delivered by a prophet. He reminds the church that God should be in control of the service and, since He is a God of order, the message He wants delivered should be shared so the church can be built up in the faith.