Principal English Translation: 

barn swallow, a bird (see Hunn, attestations)

Alonso de Molina: 

cuicuitzcatl. golondrina.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 26v. col. 2. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

CUĪCUĪTZCA-TL pl: -MEH swallow (bird) / golondrina (M) [(2)Cf.4r,(2)Zp.63,149]. Z has the variant CUICUĪTZCĀNI, once with the vowels of the second and third syllable marked long and once with no vowels marked long. CUICUĪTZCĀNI See CUĪCUĪTZCA-TL.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 71.

Attestations from sources in English: 

CUĪCUĪTZCA-TL, Barn Swallow (Hirundo rustica) [FC: 28 Cujcujtzcatl] “It is small and black, with small, pointed bill, with small, short legs. It is charcoal-colored, very black.... It is a warbler, a crier … an awakener of the sleeping. It is a builder of mud nests in house roofs, in house fronts. It is a traveler, a disappearer…. It flutters, it cleans itself, beautifies itself; it hurls itself into the water, it bathes itself.” There are three species of mud-nest building Mexican swallows. The description fits the Barn Swallow best.
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 11 – Earthly Things, no. 14, Part XII, 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, 1963); and, with quotation selections, synthesis, and analysis here also appearing in E. S. Hunn, "The Aztec Fascination with Birds: Deciphering Sixteenth-Century Sources," unpublished manuscript, 2022, cited here with permission.