Desencadeno comes from the verb desencadenar, which literally means 'to unchain,' from the root word cadena (chain). It's a powerful and dramatic word for unleashing something.
In the song, Alvaro Soler sings, "Contigo me desencadeno" (With you, I unleash myself). He uses this word to describe breaking free from his inhibitions and unleashing his true, powerful, inner 'animal', all thanks to the strength someone gives him.
Spanish singer Alvaro Soler brings huge, battle-ready energy to this track, using wild beast imagery to talk about breaking past your own limits. He kicks things off by calling his spirit "noble como un león" (noble like a lion) and urges you to remember that your imagination has no boundaries. The fight he is preparing for is not a solo grudge match, though. He explains that his soul is anchored by someone special with "amarrada por mi calma / mi calma eres tú" (tied down by my calm / my calm is you). It sounds gentle, but that calm is actually what keeps him from flying off the handle until the right second.
Once that anchor unhooks, he goes all out. He shouts "contigo me desencadeno" (with you I unleash myself, or unchain myself) and invites this partner right into his ring ("ahora entra en mi terreno" [now enter my turf]). Instead of living with fear ("cómo vas a vivir con miedo" [how are you going to live with fear]), he channels everything into raw drive, swearing "hoy lucharé como un animal" (today I will fight like an animal). The sweet twist is that despite all the roaring and banners waving in the wind, any triumph belongs entirely to friendship: "si hoy voy a triunfar / no voy a olvidar / que por ti será / por tu amistad" (if today I succeed, I will not forget that it will be because of you, because of your friendship).