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"Aquello" is a pronoun which is often translated as "that", and "eso" is a pronoun which is also often translated as "that". Learn more about the difference between "aquello" and "eso" below.
aquello()
A pronoun is a word that stands in for a noun (e.g., she).
eso()
A pronoun is a word that stands in for a noun (e.g., she).