From Portuguese phonetics, we can glimpse the Badajoz word Cheles, from the Latin planellas, referring to the flatness of the terrain, although there are doubts as to its etymology and motivation. The ending -es has also been seen as a Mozarabism. See Castaño Fernández (120-121).

Cited bibliography:

Castaño Fernández, Antonio M. Los nombres de Extremadura. Estudios de toponimia extremeña. Mérida: Editora Regional de Extremadura, 2004.