It is a toponymic surname, meaning it comes from a place name. Specifically, it originated from the town of Sandoval in the province of Navarra, Spain.
The name itself is likely derived from the Basque word "sandu", which means "saint" or "holy", combined with the suffix "-bal", which can indicate a place or valley.
Therefore, Sandoval likely originally referred to someone who came from or lived near a place associated with a saint or a holy valley.