Learn Hardcore Spanish (Latin America): Los que viajan solo con equipaje de mano pasan más rápido en el aeropuerto. - Those who travel only with carry-on luggage get through faster at the airport.

It means those who or the ones who. It’s the definite article los (the) plus the relative pronoun que (who/that). It introduces a clause that describes a group in general.

If referring to only women: Las que
Singular: El que / La que
For things/abstract ideas (not people): Lo que = what/that which
Another option for people: Quienes = those who (more formal)

Why can’t I say Ellos que viajan…?

Because subject pronouns like ellos don’t introduce relative clauses. Spanish uses los que or quienes to mean “those who.” So use Los que viajan… or Quienes viajan…, not Ellos que….

Why is it viajan (simple present) and not están viajando (present progressive)?

Spanish normally uses the simple present for general truths/habits. The sentence makes a general statement. Están viajando is used when the action is happening right now.

What does solo mean here, and why no accent on it?

Here solo is an adverb meaning only. Current standard spelling doesn’t require an accent (RAE: accentless), though sólo is still optionally used by some to avoid ambiguity. You can always use solamente instead. Note: solo/sola as an adjective means alone, which is a different meaning.

Is the placement of solo okay? Can it go elsewhere?

Yes. Common options:

viajan solo con equipaje de mano (clear: only with carry-on)
solo viajan con equipaje de mano
viajan con solo equipaje de mano
Replace with solamente in the same spots. To avoid ambiguity, put solo right before what you’re restricting: solo con equipaje de mano is very clear.

Why is equipaje singular? Why not equipajes?

El equipaje is a mass/uncountable noun (luggage), so it’s normally singular even if it includes multiple bags. If you want to count, use words like maletas (suitcases), bolsos (bags), or valijas (Southern Cone).

What does equipaje de mano literally mean, and are there regional alternatives?

Literally “hand luggage,” i.e., carry-on. Alternatives:

maleta de mano (carry-on suitcase)
bolso de mano (carry-on bag)
valija de mano (Argentina/Uruguay) All are widely understood in Latin America; equipaje de mano is standard.

What does pasan mean here? Is it “pass” like “go through”?

Yes. Pasar can mean to move along/get through. Here it’s intransitive: they get through faster. You can add specifics:

pasan por seguridad (go through security)
pasan migración (go through immigration)
pasan por el aeropuerto (move through the airport)

Why pasan más rápido and not más rápidamente?

Both are correct. In everyday Latin American Spanish, the adjective rápido is very commonly used adverbially (meaning “fast/quickly”). Rápidamente is a bit more formal. Another (more Peninsular) option is más deprisa.

Should rápido agree in number or gender with los que?

Not here. When rápido functions adverbially (quickly), it doesn’t change. You’d only make it agree if it’s an adjective modifying a noun:

Adverb: pasan rápido
Adjective: trámites rápidos (fast procedures)

Why does más have an accent, but solo doesn’t?

Más meaning “more” always carries an accent. Mas without an accent means “but” (rare/archaic). For solo/soló, current standard is no accent when it means “only,” with an optional accent (sólo) only to avoid genuine ambiguity. Also note rápido always has an accent on the first syllable.

Why is it en el aeropuerto and not just en aeropuerto?

Spanish normally uses the definite article with singular countable nouns in generic location phrases. El aeropuerto is masculine, so en el aeropuerto. You could say en un aeropuerto to mean “at an airport (any airport).”

Can I say por el aeropuerto instead of en el aeropuerto?

Yes, but there’s a nuance:

en el aeropuerto = at/in the airport (location/context)
por el aeropuerto = through/around the airport (path/movement) Both can fit here; por emphasizes moving through the space.

Can I replace Los que with Quienes or Las personas que?

Yes:

Quienes viajan solo con equipaje de mano… (a bit more formal)
Las personas que viajan solo con equipaje de mano… (more explicit)

Why can’t I say Los viajan…?

Because los alone is just the article “the.” To mean “those who,” you need los que (or quienes). Los viajan is ungrammatical.

Do I need to say más rápido que… to make the comparison explicit?

Not required. Spanish often leaves the comparison implicit. You can add it if you want: pasan más rápido que los demás / que otros pasajeros.

Is the word order fixed, or can I move parts around?

You can reorder for emphasis:

En el aeropuerto, los que viajan solo con equipaje de mano pasan más rápido.
Pasan más rápido en el aeropuerto los que viajan solo con equipaje de mano. All are grammatical; the original is the most neutral.