What does Liu Xu mean?

Liu Wu: Wuzi, Wuyin, Chen Wu, Wuwu, Wushen and Wuxu.

The ancients used ten-day stems of "A, B, C, D, E, G, G, E, G" and twelve branches of "Zi Chou Mao Yinchen has arrived in Shen You at noon" to form sixty Jiazi. According to the arrangement order of 60 jiazi, it is pushed from the old yellow calendar, and it is a round every 60 days. Among them, Wuzi, Wuyin, Chen Wu, Wuwu, Wushen and Wuxu are called five days every six days, also known as "Liu Wu". On June 5th, no digging, no cutting, no chanting, no ringing of bells and drums, and no singing of pilgrims are allowed to reduce the occurrence of bad disasters.