An adjective in Spanish or in English is a word used to describe a noun (for example: size, color, shape, etc.).
An adjective agrees in gender and number with the noun it modifies. Similar to nouns, an adjective usually end in -o for masculine and -os for masculine plural; -a for feminine and -as for feminine plural.
un hombre gordo
una novia fea
unos hombres gordos
unas novias feas
a fat man
an ugly girl
some tall men
some ugly girls
There are also some adjectives whose masculine singular ends in a consonant and form the feminine by adding -a:
un amigo frances
una amiga francesa
a French friend (male)
a French friend (female)
Some other adjectives ending in a consonant take the same form for both masculine and feminine:
un chico joven
una chica joven
a young boy
a young girl
Spanish adjectives are different from English adjectives. In English, adjectives are found before the noun, while in Spanish usually they're found after the noun. Also spanish adjectives agree in gender and number with the noun they modify.
Usually descriptive adjectives follow the nouns they modify
una ciudad sucia
a dirty city
When they precede the noun, such adjectives change meaning to a less literal sense.
El es un hombre pobre
El es un pobre hombre
He is a poor man (without money)
He is a poor man (with problems)
Possesive adjectives are used to show ownership or possession.
Spanish Possessive adjectives agree with the nouns they modify.
They agree with the thing possessed, not with the person.
The Possessive adjective nuesto (our), agrees in gender and number with the noun.
our (masculine singular)
our (feminine singular)
our (masculine plural)
our (feminine plural)