"And it shall come to pass in the last days, God declares, that I will pour out of My Spirit upon all mankind, and your sons and your daughters shall prophesy [telling forth the divine counsels] and your young men shall see visions [divinely granted appearances], and your old men shall dream [divinely suggested] dreams."
Prophecy means a message from God. When spoken it should be edifying and encouraging and given with the love of the Lord. The person bringing the prophecy should be completely dependent on the Holy Spirit. 1 Corinthians 12 : 11 says " All these [gifts, achievements, abilities] are inspired and brought to pass by one and the same [Holy] Spirit, Who apportions to each person individually [exactly] as He chooses.
Some years ago I was working with a young girl who I was very fond of, we had become very close. One night I had a dream about her. I dreamt she was pregnant and in the dream I sensed she was concerned about her future. When I awoke I knew that it was not just an ordinary dream. I had no idea she was pregnant. I asked the Lord about it and felt that I was to tell her what He had shown me. When I spoke with her she confirmed that she had just become pregnant and asked me if everything would be OK. I was able to reassure her that God had a wonderful plan for her and her baby. She did give birth to a healthy little babe and went on to marry the father of the child and they have a very happy family.
We can read about prophecy all through the bible. One of my favorite passages is in Daniel 4. The King, Nebuchadnezzar, has a dream and Daniel is able to interpret the dream and then give counsel to the King. There are also many prophecies about the Jewish people which have come to pass. Isaiah 66 : 8 speaks of a nation being born in one day. I believe this came to pass on May 14, 1948, when David Ben-Gurion, the head of the Jewish Agency, proclaimed the establishment of the State of Israel. Then US President Harry S. Truman recognized the new nation on the same day. Also the Prophet Isaiah in Chapter 53 speaks about the Messiah Jesus who was yet to come and die for the sins of all mankind. This happened 700 years before His birth. In Amos 3:7 " Surely the Lord God will do nothing without revealing His secret to His servants the prophets."
In conclusion, in his first letter to the church in Corinth, Paul writes about the gifts of the Holy Spirit in Chapter 12 : 31 "And yet I will show you a still more excellent way [one that is better by far and the highest of them all] - love."