Chivalry is:
the medieval knightly system with its religious, moral, and social code.
the combination of qualities expected of an ideal knight, especially courage, honor, courtesy, justice, and a readiness to help the weak.
courteous behavior, esp. that of a man toward women.
So, some characteristics would be to hold the door and say “after you”, to pay for a meal, to pull out a chair before someone sits, and many other kind, mannerly gestures