Learn Italian: Questi fiori sono belli. Li compro. - These flowers are beautiful. I buy them.

In Italian, direct object pronouns like li (them) generally go right before the conjugated verb. While in English we say "I buy them," the Italian structure translates literally to "Them I buy" (Li compro).

How do we know to use li for "them" here instead of le?

The pronoun has to match the gender and number of the noun it replaces. We are replacing questi fiori (these flowers). Because fiore (flower) is a masculine noun, we use the masculine plural pronoun li. If we were replacing feminine plural objects, we would use le.

Why is the word for "these" questi?

Words like questo (this) change their endings to match the gender and number of the noun they describe. Since fiori is masculine plural, questo changes to its masculine plural form, questi.

Since the singular is fiore, how do I know if words ending in -e are masculine or feminine?

Nouns ending in -e in the singular can be either masculine or feminine, and you usually just have to memorize their gender. However, you can spot that fiore is masculine right here in the sentence because the words describing it (questi, belli) use masculine plural endings!