This is the eighth month of the Hebrew calendar. The fifteenth day is near the beginning of November on Western calendars. Alternate translation: "on the fifteenth day of the eighth month" (See: [[rc://en/ta/man/jit/translate-hebrewmonths]] and [[rc://en/ta/man/jit/translate-ordinal]])
"Went up" here is an idiom for going to a sacred place to worship since these altars were located on high places. Alternate translation: "offered sacrifices on the altar" (See: [[rc://en/ta/man/jit/figs-idiom]])