He declares what has been and what is to be, and he reveals the tracks of hidden things (Sirach 42:19).
"When the Spirit of truth comes, he will guide you into all the truth;
for he will not speak on his own authority, but whatever he hears he will speak,
and he will declare to you the things that are to come."
John 16:13
Prophecy is a gift of grace in proportion to faith.
Having gifts that differ according to the grace given to us, let us use them: if prophecy, in proportion to our faith. (Romans 12:6)
Prophecy is an inspired declaration of divine will and purpose
Prophecy is not just a prediction of things to come. More than this, prophecy is an inspired declaration of divine will and purpose (Merriam-Webster).