"oh, how good [something] is" (especially, admiring one self) (see Molina)
Orthographic Variants:
yeinicqualli, ye inic qualli
Alonso de Molina:
yeinicqualli. o quan buena cosa es. &c sic de alijs. admirandose. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 35r. col. 2. Thanks to Joe Campbell for providing the transcription.