un (masculine singular)
una (femine singular)
unos (masculine plural)
unas (femine plural)
a) "Un, una" are the singular form, and are used to express just one object:
un gato (one cat, a cat)
un libro (one book, a book)
un lapicero (one pen, a pen)
una camisa (one shirt, a shirt)
una mesa (one table, a table)
una silla (one chair, a chair)
b) "unos, unas" are the plural forms, the are equivalent to "some" in english, they give an idea about few objects.
unos gatos (some male cats)
unos libros (some books)
unos hombres (some men)
unas personas (some persons)
unas carpetas (some desks)
unas medias (some socks)
*remeber when you talk about a group of objects, and into the object there's at less one "male", at this case you should use the masculine plural form. For example:
if you have 10 cats, nine of them are female cats, and the other one is a male cat, you would say:
diez gatos/ los gatos/unos gatos.... always in masculine.
here's is a table with the resumen of articles in spanish:
For remember the rules and using of plurals please go to the lesson of Plural rules:
http://mau-spanish.blogspot.com/2009/07/lesson-3-los-plurales.html
