This is a potentially dangerous and traumatic experience for your character. Is she/he time-traveling willingly?
If it's into something like medieval Europe, have them know Latin. They will at least be able to talk to priests, and can learn the local language faster.
hand gestures, the universal language
Not really. For example, the thumbs-up gesture is seen as a sign of positive approval ("A-OK") in some cultures, and an obscene phallic gesture in others.hand gestures, the universal language