In his First Epistle to the Corinthians, Paul often speaks about prophesy (προφητεύητε) as one among the skills, members of the community may have; I cite some passages:
1 Corinthians 11:4 Any man who prays or prophesies with his head covered dishonours his head, 5 but any woman who prays or prophesies with her head unveiled dishonours her head -- it is the same as if her head were shaven.
1 Corinthians 12:8 To one is given through the Spirit the utterance of wisdom, and to another the utterance of knowledge according to the same Spirit, 9 to another faith by the same Spirit, to another gifts of healing by the one Spirit, 10 to another the working of miracles, to another prophecy, to another the ability to distinguish between spirits, to another various kinds of tongues, to another the interpretation of tongues. 11 All these are inspired by one and the same Spirit, who apportions to each one individually as he wills.
1 Corinthians 12:28 And God has appointed in the church first apostles, second prophets, third teachers, then workers of miracles, then healers, helpers, administrators, speakers in various kinds of tongues. 29 Are all apostles? 29 Are all prophets? Are all teachers? Do all work miracles?
1 Corinthians 14:1 Make love your aim, and earnestly desire the spiritual gifts, especially that you may prophesy. 2 For one who speaks in a tongue speaks not to men but to God; for no one understands him, but he utters mysteries in the Spirit. 3 On the other hand, he who prophesies speaks to men for their upbuilding and encouragement and consolation. 4 He who speaks in a tongue edifies himself, but he who prophesies edifies the church. 5 Now I want you all to speak in tongues, but even more to prophesy. He who prophesies is greater than he who speaks in tongues, unless some one interprets, so that the church may be edified. 6 Now, brethren, if I come to you speaking in tongues, how shall I benefit you unless I bring you some revelation or knowledge or prophecy or teaching?
In the Jewish tradition, a prophet (נביא) was in first place a person conveying the Message of God to his people, sometimes predicting the future. In pagan Greek tradition, a prophet (προφήτος) was also someone who was said to have connections to the deities, mainly for prediction of the future. At least in the Jewish context, as we know, a prophet was an extraordinary person, not a person you may find here and there in the community.
What skill did Paul mean by prophesy/προφητεύητε?