1 Corinthians 14

The meaning of "prophet" and "prophecy" has several meanings. A common meaning is the ability to foretell future events. Another is one having a testimony of Jesus Christ received of the Holy Ghost for -

"...for the testimony of Jesus is the spirit of prophecy." (New Testament | Revelation 19:10)

A third is one that teaches true or God's doctrine and truth by the power of the Holy Ghost to comfort and edify for Moses responded -

"...would God that all the LORD's people were prophets, and that the LORD would put his spirit upon them!" (Old Testament | Numbers 11:29)

As Paul write the Corinthians on the subject of two gifts of the Spirit, speaking in tongues, and prophecy, I believe the third is what he is referring to for -

"...he that prophesieth speaketh unto men to edification, and exhortation, and comfort." (New Testament | 1 Corinthians 14:3)

The Corinthians were seemingly fixed on this idea of the gift of speaking in tongues, but Paul explained -

"He that speaketh in an unknown tongue edifieth himself; but he that prophesieth edifieth the church.
5 I would that ye all spake with tongues, but rather that ye prophesied: for greater is he that prophesieth than he that speaketh with tongues, except he interpret, that the church may receive edifying." (New Testament | 1 Corinthians 14:4 - 5)

Paul understood the greatness of the gift to teach and edify by the Spirit for -

"Yet in the church I had rather speak five words with my understanding, that by my voice I might teach others also, than ten thousand words in an unknown tongue." (New Testament | 1 Corinthians 14:19)

In all our meetings that -

"...if all prophesy [or teach and testify], and there come in one that believeth not, or one unlearned, he is convinced of all, he is judged of all:
25 And thus are the secrets of his heart made manifest; and so falling down on his face he will worship God, and report that God is in you of a truth." (New Testament | 1 Corinthians 14:24 - 25)

Therefore -

"...Let all things be done unto edifying." (New Testament | 1 Corinthians 14:26)

In modern day, the Lord explained of His prophets or teachers -

"...unto what were ye ordained?
14 To preach my gospel by the Spirit, even the Comforter which was sent forth to teach the truth." (Doctrine and Covenants | Section 50:13 - 14)

And if it so by by the Holy Ghost? -

"Wherefore, he that preacheth and he that receiveth, understand one another, and both are edified and rejoice together." (Doctrine and Covenants | Section 50:22)

There is no question that the gift of prophecy and testimony is the "best" or greater gift where in my mind, the gift of tongues -

"...are for a sign, not to them that believe, but to them that believe not..." (New Testament | 1 Corinthians 14:22)

Suggesting to me that the gift of tongues is generally given to preach the gospel (missionary work - them that believe not) in foreign lands in their own tongues.