Significance of Panchamukha Hanuman, Mahatmya of Panchamukha Hanuman is explained here. Panchamukha Hanuman (Lord Panchamukha Anjaneyaswamy) is the Lord Hanuman who appears with five faces.
The origin of Sri Panchamukha Anjaneya can be traced to a story in the Ramayana. During the Ramayana war (the war between Lord Rama and Ravana), Ravana sought the help of Mahiravana who was the King of Pathala (Netherworld). Read the full story of the origini of Panchamukha Hanuman here..
Every Face of Sri Panchamukha Hanuman has significance:
1) Sri Hanuman faces east. He grants purity of mind and success (Ishta Siddhi).
2) The Narasimha faces south. He grants victory and fearlessness (Abhishta Siddhi)
3) The west facing Garuda removes black magic and poisons (Sakala Saubhagya)
4) The north facing Varaha, showers prosperity, wealth (Dhana prapthi)
5) The Hayagriva Mukha faces the Sky. But since we cannot see it, it is usually tilted and shown above Hanumans face. Hayagriva gives Knowledge and good children. (Sarva vidya vijaya prapthi).