Recomenzar literally means "to restart" or "to begin again." It's a less common, more emphatic way to say "start over" than simply empezar de nuevo.
In the song, the lyrics say, "Pero no tienes el valor para recomenzar" (But you don't have the courage to restart). It speaks to the difficulty of breaking free from a lie and starting fresh, making it a poignant and relatable word for anyone facing a tough decision.
Jacob Forever's "Duele" is a really honest look at the pain of being stuck in a bad situation, especially in a relationship. He starts right away with the feeling of being trapped, saying "Duele si te vas, si te quedas también" (It hurts if you leave, it hurts if you stay too). It's that feeling where no matter what you do, it's going to hurt.
He talks about the hurt of someone you care about living a lie, pretending to be happy with someone else just to please other people. "Duele que vivas en una mentira / Y le cuentes a todos que tu te sientes bien con el" (It hurts that you live in a lie / And tell everyone that you feel good with him). It's a powerful message about the courage it takes to break free from what others expect and truly live for yourself. He even says, "No hace falta ser ciego para no poder ver" (You don't need to be blind not to see), which is such a blunt way of saying the truth is often right in front of us, even if we don't want to acknowledge it.