In general, most people think of a culture as a set of behaviors belonging to a group with values, history, and traditions in common. That group may call itself a community. This does not mean that those in a common culture necessarily live in the same neighborhood or even nearby. But it does mean that they share norms for what is expected in their culture.
According to the passage, people in a community will
"Norms" are standards and patterns of social behavior. If they "share norms", that suggests that they follow the same standards. It may be likely that they speak the same language or share the same religious beliefs, but the passage doesn't state that this is necessarily true.