A determiner qualifies or determines the meaning of a noun by expressing such concepts as quantity or definiteness. Determiners are usually placed before the noun. Determiners always agree in gender and number with the nouns they modify.
Types of Determiners
Articles are the main group of determiners in Spanish. There are two categories of articles: definite and indefinite.
Definite Articles
el, la, los, las
They introduce nouns that are specific. They are translated as the in English.
Indefinite Articles
un, una, unos, unas
They introduce nouns that are not specific. They are translated as a or an in English.
Possessive Determiners
mi, mis, tu, tus, su, sus, nuestro, nuestra, nuestros, nuestras
They indicate ownership or possession like my, your, his, her, our, their.
Demonstrative Determiners
este, esta, ese, esa, aquel, aquella, etc.
They point out something. They may be translated in English as this, that, these, those depending on the number (singular or plural) and proximity (near or far).