Huso horario literally translates to "time zone". It's a more formal and less common term than simply saying "diferencia de hora" (time difference), making it stand out.
In the song, DELAOSSA uses it to emphasize the physical distance separating him from a loved one, stating, "Un huso horario, dos mares, un trecho" (A time zone, two seas, a stretch). This highlights the geographical challenges of maintaining a connection, adding a touch of poetic realism to his longing.
DELAOSSA's "Lejos" (which means "Far" in English) is a really honest look at the loneliness that can come with chasing your dreams. The singer is out there trying to "hacer mi historia" [make my story], but he's feeling pretty down because he's far from the people he cares about. He's stuck on a plane, then without cell service for hours, and the person he messaged hasn't even read it yet! It's that classic feeling of being disconnected when you're on the road.
He talks about being in Madrid, feeling lost "en círculos sin cobertura" [in circles without coverage], and how he only knows what his friends are up to "si suben stories" [if they upload stories]. Even though he's traveling and meeting new people, he's still thinking about his mom praying for him and how he feels close to his loved ones despite "un huso horario, dos mares, un trecho" [a time zone, two seas, a stretch]. It's all about that bittersweet experience of pursuing big goals while missing the comforts of home and the people who make life meaningful. He even asks, "de qué sirven los sueños si se pierden / Mami, si no estás tú de qué me sirven los billetes" [what good are dreams if they are lost / Mom, if you are not here, what good is money to me?], which really hits hard.