"The secret" is an English equivalent of the French phrase le secret.
Specifically, the masculine singular definite article le means "the." The masculine noun secret means the same in English and French. The pronunciation will be "luh suh-kreh" in French.
"Between us" is a literal English equivalent of the French phrase entre nous. The prepositional phrase also translates as "among ourselves" or, more loosely, "(just) between you and me," according to English context. The pronunciation will be "awnt noo" in northerly French and "awn-truh noo" in southerly French.
The expression secret annexe was created for the English translation of her diary.
The English translation of sabwatan is conspiracy. The term refers to a secret plot by a group of people in order to commit something unlawful.
The word secret has the same spelling and meaning in English and French. In French it is a masculine noun pronounced "suh-kreh".
The correct spelling of "secret" in English is S-E-C-R-E-T.
The word is "rendezvous". It's French, and it indicates a meeting. The connotation in English is that the meeting is secret in some way.
Into what language?
Secret
un secret
You can say "langage secret" in French.
amour secret
secret (noun) ; secret, secrète (adjectives)