If you’re a fan of indefinite articles, then you’re in luck: Spanish gives you a range of ways to say a, an, one, and some. Believe it or not, indefinite articles in Spanish also indicate both the number and gender of their subject.
Like their cousin, the definite article the, the words a, an, one, and some come before the subject they apply to. Here are the forms of a, an, one, and some in Spanish:
un (oon) (the male a or an)
una (oo-nah) (the female a or an)
unos (oo-nohs) (the plural of un)
unas (oo-nahs) (the plural of una)
So how do you know when to use which article? It’s easy. When the noun ends in -o, it’s male. If a word ends in -a, it’s female. (Some exceptions to this rule exist, but they’re pretty easy to figure out because they follow another rule — the ma, pa, ta rule — which holds that words ending in ma, pa, and ta are likely to be masculine even though a is the last letter.) The easy part to remember is that when you see -s at the end of the word, you know the word is plural. Here are some examples:
un niño (oon nee-nyoh) (a boy)
unos niños (oo-nohs nee-nyohs) (some boys [or the children])
una niña (oo-nah nee-nyah) (a girl)
unas niñas (oo-nahs nee-nyahs) (some girls)