Principal English Translation: 

the liver (see Molina); Gordon Whittaker suggests that the visual representations of elli combine the liver with the gall bladder (personal communication 4/29/2023)

Alonso de Molina: 

elli. el higado.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 28v. col. 2. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

ĒL-LI liver / el hígado (M) In compounds this has a broader sense of ‘internal organs’ and is also associated with emotions, especially strong or unpleasant ones.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 77.

Attestations from sources in English: 

Gordon Whittaker says that terms relating to elli that start with tel- are references to being brave.
Personal communication, April 19, 2023. (SW)