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"Ellos" is a form of "ellos", a pronoun which is often translated as "they". "Canción" is a noun which is often translated as "song". Learn more about the difference between "canción" and "ellos" below.
la canción()
A feminine noun is almost always used with feminine articles and adjectives (e.g., la mujer bonita, la luna llena).
ellos()
A pronoun is a word that stands in for a noun (e.g., she).
b. them (after prepositions)
Si confías en ellos, dales las llaves.If you trust them, give them the keys.
c. them (in comparisons)
Mi hermano y yo somos tan altos como ellos.My brother and I are as tall as them.
