One of the eight parts of speech, adjectives are a type of modifier; that is, they modify or describe nouns in a certain way, letting you know the size, shape, weight, color, nationality, or any of a myriad other possible qualities of nouns.
The Spanish definite article has to agree in gender and number with the noun it modifies, and it doesn’t always correspond to an article in other languages.
Demonstrative adjectives (this, that) are used to indicate a specific noun or nouns. In Spanish, they must agree with the noun(s) in gender and number, and there are 3 different sets: este, ese, aquel.
Demonstrative pronouns (this one, that one, the one[s], these, those) refer to a previously-mentioned noun in a sentence. Spanish demonstrative pronouns are more complicated than their English counterparts, because there are three different sets and because they must agree in gender and number with the noun they replace.
The Spanish relative pronoun el cual usually means “who” or “whom” and has four different forms.
How are you feeling? Find out how to ask and answer this question in Spanish.
The aptly named indefinite article (un, una, unos, unas) indicates an unspecific or unidentified countable noun.
Indefinite pronouns are vague – they either refer to unspecific nouns (like un otro and algo) or make sweeping generalizations (cada uno, todo).