Artículo - Article
An article is a word placed before a noun to show whether the noun refers to a specific person, animal, place, thing, event or idea. Or it can be non-specific.
If it is specific it is a definite article (artículo definido)
If is it not specific it is an indefinite article (artículo indefinido)
Definite Article
I ate the apple you gave me. - Comí la manzana que me diste.
(a specific apple)
Indefinite Article
I ate an apple - Comí una manzana.
(not a specific apple)