"Arafa" is meant for "Maarifa" as "knowledge", while "Irfan" is the knowing of something with thinking and meditation. The name "Arafa" is relative to the land of Arafat, an area surrounded by mountains, nine miles from Makkah, , as a place where pilgrims gathered.
It was narrated from Imam Al-Sadiq "peace be upon him", that he said, "It was called Arafa, because angel Gabriel (peace be upon him), told the prophet Abraham, "Confess your sins there, and know your rituals". Therefore, it was called Arafa as (knowing)."
The day of Arafa is the day when the rituals of Hajj begin, as pilgrims heading to the desert of Arafat asking God Almighty for forgiveness, and that's why we still have today so many rituals like fasting, supplication and solemnity narrated from the infallible Imams "peace be upon them". In various sources, there were many Hadiths about the supplications recited at this day, including the supplication of the Holy Prophet "peace be upon him and his household" dedicated for the day of Arafa.
It was also narrated from Imam Al-Sadiq "peace be upon him", that the prophet Muhammad "peace be upon him and his household" told Imam Ali "peace be upon him", "May I teach you a supplication of the day of Arafa, as it was a supplication for all prophets before me?", then Imam Ali replied ""Yes , messenger of Allah", so the prophet did. Therefore, this supplication passed down by Imams until today.
Sources:
Al-Mufaradat, by Al-Rraghib Al-Asfhani [p 343].
Al-Tahqiq fi Kalimat Al-Quran Al-Karim, by Al-Mostafawi, [Vol. 8, p. 100].
