Comparing to English articles, Spanish articles have different forms depending on number and gender. So, it might be a little bit tricky.
First, I would like to do the definite articles (“the” in English)
Definite articles “el” and “los” are used for male nouns in singular and plural forms
E.g. El niño (the boy)
Los niños (the boys/the boys and girls)
*If a group contains both male and female content, the group become masculine plural. Thus “los niños” could have 2 meanings in this case.
Definite articles “la” and “las” are used for female nouns in singular and plural forms.
E.g. La mujer (the woman)
Las mujeres (the women)
Definite article is used to express the specific things or things in general.
¿Tú conoces la chica que conocí en la fiesta de la semana pasada?
Do you know the (specific) girl that I met at the party last week?
No me gustan las matemáticas. I do not like mathematics. (in general)
Indefinite articles also have different forms depending on the gender and numbers of noun. (In English “a” or “an”)
Indefinite article is used to express the unspecified things
Quiero encontrar una mujer hermosa. I want to meet a beautiful girl.
Necesito comprar un carro para vivir aquí. I need a car to live here.