Articles are words used before nouns to indicate whether the nouns are specific or general. In Spanish, there are definite articles ("el," "la," "los," "las") which correspond to "the" in English and signify a specific noun, and indefinite articles ("un," "una," "unos," "unas") which correspond to "a," "an," or "some" in English and refer to non-specific nouns. Understanding how to use articles correctly is essential for proper sentence structure and meaning.