Nouns in Italian are either masculine (maschile) or feminine (femminile). They can also be singular (singolare) or plural (plurale). This is what we mean by gender and number, respectively. Gender and number are important to learn because they will have an impact on other aspects of Italian grammar that you will learn.
Women, especially, when learning Italian should always remember to use the feminine when talking about themselves (Sono brava or Sono stata a Napoli) since most textbooks tend to use the masculine standard.
As a rule, nouns ending in -o are masculine. Nouns ending in -a are usually feminine.
masculine: amico, biglietto, campo, telefonino
feminine: amica, carta, mela, macchina
Nouns that end in -e can be either masculine or feminine
masculine: studente, ristorante, affare
feminine: carne, nozze, stazione, immigrazione
Nouns that end in consontants generally are masculine.
bar, internet, browser, film, sport
Italian nouns indicate number based on their endings:
Singular nouns ending -ca or -ga as well as many nouns ending in -go require an “h” to keep the hard “g” (such as: go, gone, game):
amica -> amiche
acciuga -> acciughe
borgo -> borghi
There are also invariable nouns: nouns which have the same singular and plural and do not change. Invariable nouns generally end in an accented vowel, a consonant, can be abbreviated or are foreign words.
caffè, film, cinema, città, metro
Nouns ending in -io can be tricky. If the “i” in the -io is stressed, then the “i” is doubled in the plural, as in zio and invio:
zio -> zii
invio -> invii
If the “i” is unstressed, as in negozio or municipio, then the plural is formed by dropping the “o”. For example:
negozio -> negozi
municipio -> municipi