un or el: the article decides whether we already know

The article answers one question: does the listener already know which one we mean? New things are introduced with un / una; known things are picked up with el / la — exactly the division of labour between English 'a' and 'the'. For example: “Hay un problema en la cocina” — There's a problem in the kitchen. A rule from the Spanish course: worked out on examples, not memorized as a wording.

Updated September 1, 2026 · Lingofly

How it works

The article answers one question: does the listener already know which one we mean? New things are introduced with un / una; known things are picked up with el / la — exactly the division of labour between English 'a' and 'the'.

It shows most clearly in the pair hay and está. Hay una farmacia en esta calle — there's a pharmacy on this street, one you hadn't heard of. La farmacia está al lado del banco — the pharmacy, the one we both know, is next to the bank. That's why el almost never follows hay: there is no way to announce the existence of something the listener already knows about.

Plurals are made two ways: -s after a vowel (la mesa → las mesas), -es after a consonant (el hospital → los hospitales). A final -z turns into c: el lápiz → los lápices.

Some words simply have no singular: las vacaciones (vacation), los deberes (homework), las gafas (glasses). 'Un deber' exists, but it means 'a duty', not homework.

Table

un or el: the article decides whether we already know
onemany
known, masculineel vecinolos vecinos
known, femininela llavelas llaves
new, masculineun vecinounos vecinos
new, feminineuna llaveunas llaves

By example

  • Hay un problema en la cocina
    There's a problem in the kitchen
  • La habitación tiene dos ventanas
    The room has two windows
  • Estoy de vacaciones hasta el lunes
    I'm on vacation until Monday

How the rule settles in your head

A rule is not memorized from an explanation. It is memorized from an attempt to use it and a mistake — that is why the app delivers it mixed in with words, not as a separate lesson: it resurfaces exactly where you forgot it.

Frequently asked

Un vs el in Spanish?

The article answers one question: does the listener already know which one we mean? New things are introduced with un / una; known things are picked up with el / la — exactly the division of labour between English 'a' and 'the'.

Hay vs está?

It shows most clearly in the pair hay and está. Hay una farmacia en esta calle — there's a pharmacy on this street, one you hadn't heard of. La farmacia está al lado del banco — the pharmacy, the one we both know, is next to the bank. That's why el almost never follows hay: there is no way to…

When to use un and when el?

Plurals are made two ways: -s after a vowel (la mesa → las mesas), -es after a consonant (el hospital → los hospitales). A final -z turns into c: el lápiz → los lápices.

Why hay una farmacia, not hay la farmacia?

Some words simply have no singular: las vacaciones (vacation), los deberes (homework), las gafas (glasses). 'Un deber' exists, but it means 'a duty', not homework.

Los and las: which Spanish article to use?

Some words simply have no singular: las vacaciones (vacation), los deberes (homework), las gafas (glasses). 'Un deber' exists, but it means 'a duty', not homework.

What does it look like in an example sentence Spanish?

“Hay un problema en la cocina” — There's a problem in the kitchen. A rule is easier to test on sentences like this than to memorize as a wording: what surfaces in conversation is the sentence.

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Test the rule on examplesPractice