Psiquis translates to "psyche" in English, referring to the human soul, mind, or spirit. It's a more formal and less common word than 'mente' (mind), making it stand out in a song.
In the lyrics, KHEA sings, "Después volver a hacerlo para no saciar mi psiquis, nah" (Then do it again so as not to satisfy my psyche, nah). He uses it to convey a deeper, almost insatiable desire or need that goes beyond simple material satisfaction, hinting at a complex inner world.
KHEA opens this one parked somewhere with a drink in his hand, more caught up in weed and whiskey than in actually calling the person he can't stop thinking about. "Sigo sin llamarte porque me da miedo, really" [I still haven't called you because it scares me, really] is basically the whole song: he wants to reach out and won't let himself.
The chorus turns that hesitation into an image: "Las estrellas ya no brillan en la noche" [The stars no longer shine at night]. It isn't really about the sky, it's about not knowing if she's even still out there for him. By the second verse he stops dodging it and owns the damage: "Nunca te hice caso, sé que te descuidé" [I never paid attention to you, I know I neglected you], and admits sorry won't cut it: "Sé que no sirve un perdón, mucho menos un millón" [I know an apology is useless, much less a million]. He leaves the door open anyway, telling her "ya tú sabes que pa' ti acá hay un lugar" [you know there's a place for you here], torpe as ever and not pretending otherwise.