Bilingualism means a society understand and speak two languages and can communicate using both languages fluent. It does not mean that everyone must speak both languages.
Bilingualism means a society that understands and bilingual. And can communicate using both languages fluently. Respectively does not mean that all people must speak both languages.
Bilingualism means society understand and speak two languages. And able to communicate using both languages fluently. At any rate does not mean that all people must speak both languages.