Translation:There are various books on the desk.
Ciao ragazzi, precisely diverso is one of those adjectives that changes meaning depending on the placement:
Ci sono diversi libri. → There are various/diverse books.
Ci sono libri diversi. → There are different/diverse books.
So in this phrase only the first one :-)
I had written the rules about the placement in this old discussion, with some other examples about these types of adjectives as well:
Do you mean diverse in Italian or diverse in English? Diverse in italian is feminine plural, libri is masculine plural, thus you have to write 'diversi'.
From looking at the comments about using diverse in the English sentence, there are a couple of possible problems: 1) Adjective placement before or after the noun affects the meaning - diversi informazioni = some/various information while informazioni diversi = different information 2) I wonder if Duo is seeing the English word diverse in the English sentence (which we all agree is being used correctly to mean various and different) as the Italian word 'diverse' which it interpretes as being Italian not English and having the wrong form and agreement for the noun, thus marking it wrong?