Principal English Translation: 

on the face, or on the surface of something (see Molina); or, in the presence of (see attestations)

Alonso de Molina: 

ixco. enla cara, o enla sobrehaz.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 45r. col. 1. Thanks to Joe Campbell for providing the transcription.

Attestations from sources in English: 

ic mitoaia onacoqujxtilo in quauhtecatl, iehica ca iaomjquj, ixco iauh, ixcopa itztiuh, ixco monoltitoc in tonatiuh, qujtoznequj, amo mictlan iauh = This was called “the sending upward of the eagle man”: because he who died in war went into the presence of [the sun]: he went before and rested in the presence of the sun. That is, he did not go to the land of the dead. (sixteenth century, Mexico City)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 2—The Ceremonies, No. 14, Part III, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1951), 48.