Complex sentence: Xibalba is described in the Popol Vuh as a court below the surface of the Earth associated with death and with twelve gods or powerful rulers known as the Lords of Xibalba.
Split into simpler sentences: Xibalba is described in the Popol Vuh as a court below the surface of the Earth. The place Xibalba was associated with death and was ruled by twelve gods or powerful rulers known as the Lords of Xibalba.