As there are many examples of. significant dreams given by God to heathens, as Ge 41 Da 2 Da 4, so some of them had the gift of interpreting dreams; which they sometimes did by study and art, and sometimes by Divine direction, as in this case.
Related Commentaries of Judges 7:14
Judges 7:14
14 And his fellow answered and said, This is nothing else save the sword of Gideon the son of Joash, a man of Israel: for into his hand hath God delivered Midian, and all the host.