Italian: Grammar > Plural
In case of masculine nouns the plural is usually formed by adding -i to the end of a noun, or in case the noun ends in a vowel by changing this vowel to -i. The definite article is changed to i.
In case of feminine nouns the plural is usually formed by adding -e to the end of a noun, or in case the noun ends in a vowel by changing this vowel to -e. The definite article is changed to le.
il ragazzo, i ragazzi (the boy, the boys)
la ragazza, le ragazze (the girl, the girls)
There are quite some irregular nouns which deviate from these rules. For example:
il caffè, i caffè (the coffee, the coffees)
In the latter example you see the the singular is masculine, but the plural has taken the feminine gender.
il braccio, le braccia (the arm, the arms)