to agree or give consent by nodding, or beckoning someone in this way (see Molina)
Alonso de Molina:
ixcuecuechoa. n. (pret. onixcuecuecho.) consentir abaxando la cabeza, o llamar a otro assi. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 45r. col. 2. Thanks to Joe Campbell for providing the transcription.