1. A clause expressing permission, wishes, or circumstances allowing someone to rest or take a break
I hope that you can rest after all this hard work.
Espero que podes descansar depois de todo este trabalho duro.
2. Used in imperative or subjunctive contexts to grant someone the ability or opportunity to relax
Rest assured that you can relax now.
Fica tranquilo que podes descansar agora.