Translation
The one who speaks in an [unknown] tongue edifies himself, but the one who prophesies edifies the called-out-ones.
Go to footnote numberParaphrase
According to what you say, the person who prays in tongues even in public (which should not happen), is personally strengthened by it himself (even though this is not the purpose of the spiritual gifts, they are always for helping others), in contrast the one who prophesies is the one who truly does strengthen other followers of Jesus in the assembly of the church.
Footnotes
1: "the called out ones"
This is the Greek word for the church. It refers to those who have responded to God’s call to come out from the world and assemble together as followers of God.
THESE BURDENS SHOULD BE EXPRESSED IN PRIVATE, NOT IN PUBLIC
While burdens can be expressed in various ways, there are proper and improper places for expressing them. At first glance this verse seems to present a simple contrast, but that cannot be the case. It is simply not true that any proper form of tongues was intended by God to edify only the person speaking in tongues. All spiritual gifts were given by the Holy Spirit in order to edify other people. Paul’s statement about prophecy is true, but his statement about tongues seems to be mimicking what they were reported to be saying about tongues, which contradicted everything Paul had ever taught about the purpose of the gifts of the Spirit. Verses two, three and now four all seem to be referring to the counterfeit they had devised because what is described violated at least one rule about spiritual gifts. Therefore, this verse lends itself readily to a mimicking rendering, not a simple explanation. I see no other interpretation as viable.
This is not the only time something like this is stated. You will notice various times in this chapter, as well as what we saw in I Cor 12, that all spiritual gifts have been given for the edification of others; they are not for personal use or benefit.
You may wonder how I can say that these burdens should be expressed in private, and then say that all the undeserved gifts of the spirit should benefit others, not self. My answer is that carrying a burden for someone else is about them, not about self. It is weighty work to carry such a burden. It drives us to pray to God for that person. It causes us to look for opportunities to minister to them. Indeed, such burdens end up being for the good of others, even though they start out as a private ministry that no one else knows about.