preceded by a number, means that many twenties of people [or other countable things, such as agave plants, furros, etc.], just like -pōhualli in general
Visually, the tecpantli in Nahuatl hieroglyphs is a flag or banner, but should be seen as a number or a reference to a row, line, etc., of things that are counted. As Gordon Whittaker explains (Deciphering Aztec Hieroglyphs (2021), this flag is not to be confused with panitl, or pamitl (in Tetzcoco), and never simply pantli. But pantli will be found in association with a number in texts referring to things that are counted. See examples in our entry for pantli (link below).
yetecpantli onchiuhcnahui tlacatl = 69 people (early seventeenth century, central New Spain)
ome tecPantli metl = 40 magueyes (San Pablo Tepemaxalco, Toluca Valley, 1695)
nauchtecpan [sic] tlamamatli xochicacauatl = four hundred cargas de cacao
macuiltecpantli mamalli cacauatl = five fardos de cacao, where a fardo is a bale of goods, a bundle, a package
centecpac tlamamalli cacahuatl = one carga de cacao
Tribute labor arrangements were, prior to contact, probably made in groups of twenty people (centecpantli), given the vigesimal numbering system. But after contact, Europeans many have preferred groups of five twenties (macuiltecpantli, one hundred), given their decimal numbering system. We see macuiltecpantli as very common in the Ordenanzas de Cuauhtinchan. (Puebla, sixteenth century)
Auh ynin cenca ypan tlatozque y macuiltecpanpixque yvan ayac ichtaca monamictizque auh in iquac yn acame monamictitivi tevicaz in centecpanpixqui anoҫo tequitlato = Y sobre esto tendrán mucho cuidado los macuiltecpanpixque para que nadie se case en secreto. Y cuando algunos vayan a casarse, el centecpanpixqui o el tequitlato los llevarán (Cuauhtinchan, Puebla, s. XVI)
calacuemitl yvan oquipopolo metli chicuetecpantli yvan centetl calli oquixitini = tiene casas con predios, destruyo ciento sesenta magueyes y destruyo una casa (Tlaxcala, 1567)
centecpantli on matlactli = "beynte o beynte y cinco [sic pro: treinta]" (México, 1558)
Cuando se cuenta por veintenas, se usan tres desinencias, según los casos: tecpantli, ipilli, y quimilli. Tecpantli se utiliza para [contar a las] personas.
yn ovejas cequi carneros porecos chicuetzontli yhuan matlacpoualli auh oncan quinhuicatinemi cabras ontecpantli ynin çan mocenpiazque = ovejas y carneros, y borregos son por todo ocho mil y docientas cabezas, y las cabras dos pastorías, éstas se han de mantener en ser (Tetepango, Hidalgo, 1586)