When do you use un, una, unos, unas?
The indefinite article introduces a noun that is new or unspecified — the job English gives to a and an. Spanish has the same two singular forms, plus a plural that English lacks entirely.
The choice works differently, though. English picks a or an by the sound that follows: a book, an apple. Spanish ignores the sound and picks by the gender and number of the noun, so you have to know whether the noun is masculine or feminine.
The four forms
| Gender | Singular | Plural |
|---|---|---|
| masculine | un libro | unos libros |
| feminine | una casa | unas casas |
Singular: un and una
Masculine nouns take un, feminine nouns take una. Since nothing in the English word tells you which is which, pick up the gender with every new noun you learn.
Tengo un coche nuevo.
I have a new car.
Hay una farmacia cerca.
There is a pharmacy nearby.
Es una buena idea.
It is a good idea.
Plural: unos and unas (some, a few)
English has no plural of a, so unos and unas land somewhere near some or a few. They are not obligatory: Spanish can leave them out just as English can, and dropping them makes the statement more general.
Necesito unos minutos.
I need a few minutes.
Compro unas flores.
I am buying some flowers.
Tengo unas preguntas.
I have a few questions.
Jobs and nationalities: no article
After ser, occupations and nationalities take no indefinite article. English always says I am a teacher; Spanish simply names the category: not Soy un médico but Soy médico. As soon as an adjective joins in, the article comes back.
Ella es profesora.
She is a teacher.
Soy alemana.
I am German.
Es una buena profesora.
She is a good teacher.
