There are a few different views about the reason of naming the aforesaid day as “ashura”. One states that since it is the 10th day of Muharram, it is called so; while the other believes, it is named so, because Allah (swt) bestowed His ten prophets ten kinds of bounties on this special day,
Actually, The Day of Ashura, which is the common date of various events concerning the history of humanity, is significant not only for Muslims, but also for the other two Semitic religions; Judaism, Christianity. It is significant for the Jews, as Prophet Moses was saved from the tyranny of Pharaoh on the Day of Ashura. In order to respect this special day, the Jews spent it fasting.