The phrase "to watch over" means to keep an eye on, supervise or monitor something or someone. It can refer to actively paying attention and taking care of a situation, person or thing in order to ensure that everything is okay. This expression can be used both literally and figuratively - for example, one might say "I will watch over the children while you are away" meaning they will keep an eye on them, or "The guardian angel watched over me during my journey." In this context it means a divine being was looking out for their safety.