This is the seventh month of the Hebrew calendar. The tenth day is near the end of September on Western calendars. (See: [[rc://en/ta/man/jit/translate-hebrewmonths]] and [[rc://en/ta/man/jit/translate-ordinal]])
On this day each year the high priest would make a sacrifice to Yahweh so that Yahweh would forgive all the sins of the people of Israel. See how you translated this in [Leviticus 23:27](../23/27.md).