An Italian adjective changes to match its noun — masculine or feminine, singular or plural. There are two main types:

Type	Masc. sing.	Fem. sing.	Masc. plural	Fem. plural
-o adjectives	piccolo	piccola	piccoli	piccole
-e adjectives	grande	grande	grandi	grandi

• un libro piccolo, una casa piccola, i libri piccoli, le case piccole
• un giardino grande, una piazza grande, i giardini grandi, le piazze grandi

Adjectives in -e don't care about gender — only about number.