The word renaciste is the preterite form of renacer in the second person singular. There are other translations for this conjugation.
See the full renacer conjugation

renacer

Ése día, a la orilla del río, fue el momento que "renaciste".
That day, by the edge of the river, that was the moment you were reborn.
Renaciste en un buen momento. Espera... o quizás nunca conociste el placer de ser una mujer.
You were reborn at a really nice time or perhaps you didn't have the chance to know the pleasure of a woman yet?
Want to Learn Spanish?
Spanish learning for everyone. For free.
SpanishDict Premium
Have you tried it yet? Here's what's included:
Cheat sheets
No ads
Learn offline on iOS
Fun phrasebooks
Learn Spanish faster
Support SpanishDict