de a de veras is a colloquial Mexican expression that means "truly" or "for real." It's an emphatic version of the more common phrase "de veras" (really).
In the song, Xavi sings "Te quiero, yo te quiero de a de veras" to express that his love is absolutely genuine and sincere, not just a fleeting feeling. Learning this phrase is a great way to add authentic, heartfelt emphasis to your Spanish.
Hey, have you heard Xavi's "Te Quiero"? It's such a sweet song where he's basically pouring his heart out to someone he really cares about. He knows there are "rumores" [rumors] going around about him, and people are apparently telling her "que te puedo hacer sufrir" [that I can make you suffer]. But he's quick to shut that down, swearing "Te juro no es así" [I swear it's not like that] and insisting "Tú eres la única en mi mente" [You are the only one in my mind]. He's really trying to make it clear that despite what others say, he's loyal and committed.
He gets super romantic, telling her "Te quiero, mi corazón yo te entrego" [I love you, I give you my heart] and even admitting "Estoy loco, no lo niego" [I'm crazy, I don't deny it] – which is pretty intense! He genuinely believes "el destino nos juntó" [destiny brought us together], seeing their connection as something special, almost miraculous, saying "Entre miles de millones nos topamos... Y eso se lo debo a Dios" [Among billions of people we met... And I owe that to God]. He even says he wrote the song because he couldn't find "otra manera" [another way] to express his true feelings. It's a big declaration of love!