Deslumbras is the 'you' form of the verb deslumbrar, which literally means 'to dazzle' or 'to blind with a bright light'. It’s a beautiful and poetic word perfect for a grand compliment.
In the song, Becky G uses it to describe someone so charismatic and good-looking that they outshine everyone else in the room. She sings, "Si voy contigo deslumbras en los lugares" (When I'm with you, you dazzle everywhere), highlighting her partner's powerfully captivating presence.
This song is a back-and-forth between two people in a complicated relationship. They both have a list of complaints! He starts by saying she's not affectionate, singing, "Te mando flores y respondes otra cosa" (I send you flowers and you say something else). He feels like he's the one who has to put up with her pride. But she comes right back at him, pointing out that he gets all dressed up to go out with his friends and then is cold to her at night. She even says, "Con tu dinero todo quieres arreglar" (You want to fix everything with your money).
Despite all the fighting, they can't stay away from each other. The chorus is all about wanting to forget the problems and just be together: "Te quiero besar, ya no importa nada" (I want to kiss you, nothing else matters). She admits she actually likes his flaws, singing "a mí me gustan tus defectos" (I like your flaws), and gets super jealous when he's out. It's a messy, passionate dynamic where they believe things are getting better, even if they still feel bad sometimes.