You expect her to just randomly knows sign language in their language?
Obviously not, but I think this person was just using that as an example of nonverbal communication. If she looked and paid more attention to his facial expressions and tone of voice, she'd probably understand that he means no harm. And he too can also make a better effort, since he knows she can't understand him, he could use hand and body gestures to get at least his intentions across. Like if he had placed his palm on her forehead to check her temperature, she'd probably get that he was asking about her health
Girl please try to understand by his actions and expressions. You do know that sign language exists. Don't just go assuming things, please.