"They are not small."
Translation:Loro non sono piccoli.
"Loro non sono piccole" should be accepted as well here. "They" could refer to feminine plural too.
Why is this piccoli and not piccolo? The subject is inferred as loro, so wouldn't the adjective define this subject with a similar ending of "o"?
In Italian adjectives agree in number and gender with the noun they modify. So since "loro" is plural subject pronoun, the adjective should agree with it and also be in plural, therefore piccoli
dnovinc I understand the explanation for this part of the example. But how does 'non sono piccoli' become: "they are not small" when it seems to read: 'are not small'?
The verb "sono" is already giving us information about the subject, therefore the subject pronoun (loro = they) in Italian is not really necessary, but it can be used if we want to emphasize the subject.
"sono" can be 1st person singular [(Io) sono = I am ] and 3rd person plural [(Loro) sono = They are] form of the verb "essere=to be". In this case we also have an adjective "small", which needs to be in plural (piccoli) and by using the plural form we make it clear that we are talking about "loro".