This is the 100th most frequent Italian word.
questo
"Questo" means "this" in English.
Here, 'questo' is used as a demonstrative adjective modifying 'libro' to specify a particular book.
Questo libro è molto interessante.
This book is very interesting.
In this case, 'questo' functions as a pronoun, replacing a noun to indicate something specific left on the table.
Chi ha lasciato questo sul tavolo?
Who left this on the table?
Here, 'questo' serves as a pronoun to directly refer to something of interest or preference.