This is the 49th most frequent Italian word.
quello
"Quello" means "that" in English.
‘Quello’ is used as a pronoun referring to a specific object previously mentioned or understood from context.
Quello è il mio libro preferito.
That is my favorite book.
‘Quello’ is used as a pronoun asking about a specific event or thing that occurred.
Hai visto quello che è successo ieri?
Did you see what happened yesterday?
‘Quello’ (changed to ‘quel’ due to gender and number agreement) is used as an adjective describing the noun ‘vestito’ (dress).