"The guard knows her."
Translation:Vagten kender hende.
"Vide" is used for factual knowledge and doesn't take a direct object ("Jeg ved, at Danmark er et lille land" = I know that Denmark is a small country. "Ved du, hvad det er?" = Do you know what it is?) where as "kende" is used for nouns and people ("Jeg kende Danmark" = I know Denmark. "Jeg kender den restaurant"=I know that restaurant)