This video is talking when prophet Musa said that fasting on the day of Arafat can expiate or forgive a person's sins from the previous year and the upcoming year. Specifically, if a person fasts on the day of Arafat, motivated with the right intentions, then their sins from the year before and the year after will be forgiven by this act of fasting. So fasting on this specific day has the power to cleanse a person from sins of two whole years, according to what the prophet Musa reportedly said. The day of Arafat refers to the 9th day of Dhu al-Hijjah, the 12th month of the Islamic calendar, which is an important day of the Hajj pilgrimage.