Venciera comes from the verb vencer, meaning "to conquer" or "to overcome." It's in the imperfect subjunctive tense, which adds a layer of hypothetical desire or condition.
In the song, the singer expresses a longing for a love "que venciera feliz" (that would happily conquer/overcome). This suggests a desire for a love strong enough to overcome any obstacles and bring lasting happiness, making it a powerful and hopeful word in the context of finding true love.
Michel el Buenón's "¿Quien Sera? (En Vivo RD)" is such a fun, upbeat song about the universal quest for love! He's basically asking the big question we all wonder about: "¿Quién será la que me quiere a mí?" [Who will be the one who loves me?]
He's dreaming of finding that special person, someone who will bring back the passion and love he's felt before, maybe even make him feel it for the first time. He sings, "He querido volver a vivir la pasión y el amor que sentí" [I have wanted to live again the passion and love that I felt], and you can really feel his longing for a love that will make him happy. It's all about the hopeful search for that perfect match!