Mi casa es grande.
English: My house is big.
Possessive adjectives in Spanish are words like 'mi', 'tu', 'su', etc. They show who owns or has something. They come before the noun.
Use possessive adjectives in Spanish to say that something belongs to someone or to show relationships (like 'my book', 'your friend'). The adjective must match the number (singular/plural) and sometimes the gender of the noun.
Mi casa es grande.
English: My house is big.
Tus amigos son simpáticos.
English: Your friends are nice.
Su hermano vive en Madrid.
English: His/her/their brother lives in Madrid.
Nuestros perros son pequeños.
English: Our dogs are small.
Vuestra profesora es amable.
English: Your (plural) teacher is kind.