This pillow cover features three lines of volcanos (thus, "tres volcanes" or "three volcanoes"). This motif is typical of the traditional woven blouse (huipil) of San Juan Cotzal.
It only makes sense that volcanoes feature in designs from Guatemala, whose highlands represent one of the most active fault lines in the world. There are over 35 volcanoes in this small country, three of which are very active to this day.