Tranquilito is the diminutive form of "tranquilo," meaning "calm" or "peaceful." The suffix "-ito" adds a sense of endearment or makes it sound a bit softer and more intimate.
In this song, the singer uses "tranquilito" to express how the presence of his beloved brings him a profound sense of peace and contentment. He sings, "Es que tú tienes eso mi amor / Que me deja tranquilito" (Because you have that, my love / That leaves me calm/peaceful), highlighting the unique calming effect this person has on him.
"Tranquilito" is pure lovesick energy. The singer wakes up already wanting to see this person again: "Hoy me desperté con ganas de mirarte" [Today I woke up wanting to look at you]. They literally just saw each other yesterday, but he admits he "couldn't hold back" and even spent the whole night awake thinking of them: "Ayer ni siquiera dormí por estar pensando en ti" [Yesterday I didn't even sleep because I was thinking about you]. It feels like that early stage of love where you lose all chill and your brain is completely taken over by one person.
He also confesses the slightly embarrassing stuff we usually try to hide. He hints that he was the mysterious caller who rang and then hung up: "Tal vez pensaras que fui yo quien llamaba y te colgaba… que crees le atinaste mi amor" [Maybe you thought it was me who called and hung up on you… guess what, you were right my love]. That’s both funny and very honest. He says he needs this person next to him and begs, "Por favor ven un ratito" [Please come for a little while], because being with them is the only thing that leaves him "tranquilito" [calm, at peace]. He even compares himself to a kid with a brand‑new toy: "Estoy como niño mi amor con juguete nuevecito" [I’m like a child, my love, with a brand‑new toy]. The whole song is him openly admitting that one look from this person flipped his whole life and turned him into a lovestruck, slightly desperate, but very happy mess.