Presos literally translates to "imprisoned" or "trapped." It's a strong and evocative word that immediately brings to mind a sense of confinement and lack of freedom.
In the context of "Nova Era," the artist uses "presos" to describe a collective feeling of being stuck or constrained, perhaps by circumstances or societal pressures, preventing people from fully embracing a new era or living a new life. This metaphorical use makes it particularly impactful and memorable.
"Nova Era" opens like an announcement — "Estamos todos a viver uma era nova" (we are all living a new era) — and then spends the rest of the song explaining what the new era actually consists of. The answer arrives two verses later: "Porque estamos todos presos / Longe de pais e família" (because we are all shut in / far from parents and family). The era is a closed door, and the people behind it are the ones Nininho Vaz Maia keeps naming: the ones who still want to be happy and no longer can — "Há quem queira ser feliz e já não possa".
What gives the song its edge is the fear underneath the complaint. "E se eu parar agora / Meu Deus não serei a mesma pessoa" (and if I stop now / my God, I won't be the same person) is not about a missed night out; it is a man worried that the standing still will change him, and that the world will have moved on without him — "Meu Deus irei perder tudo lá fora" (my God, I'll lose everything out there). He never resolves the argument. He just refuses to lose it, closing on "Hai não paro agora" (I'm not stopping now), sung twice, once at the end of each half of the song.