Rendiré comes from the verb rendir, which means to surrender, yield, or give up. While it can be used in a literal sense of surrendering in battle, it often carries a deeper, more emotional or spiritual meaning.
In this song, the phrase "Rendiré mi corazón ante ti" (I will surrender my heart before you) signifies a complete and willing giving over of one's innermost self, not out of defeat, but out of devotion and love. It's a powerful expression of commitment and trust.
Danilo Montero opens this one like a confession, not a chorus. "Hay una sola cosa que yo quiero hacer" (There's only one thing I want to do), and it turns out to be handing over everything: "Yo quiero entregar mi vida en servicio y en amor a mi Señor" (I want to give my life in service and love to my Lord). Then he doesn't sing it alone. He turns to the room and asks them to say it with him: "levante sus manos conmigo y dígaselo" (raise your hands with me and tell Him).
The verse explains why the chorus needed writing. "Por mucho tiempo busqué" (For a long time I searched) "una razón de vivir" (a reason to live), and the search ends flatly: "Tu amor me respondió" (Your love answered me). What follows repeats so many times it stops sounding like a chorus and starts sounding like a vow you're making along with him: "Tú serás mi pasión" (You will be my passion), "Y mis pasos se guiarán por tu voz" (And my steps will be guided by Your voice), until the whole song narrows down to two words: "Mi Jesús y mi Rey" (My Jesus and my King).