Garçon doux in French means "sweet boy" in English. This is never used in French.
A billet-doux is a love letter.
Douce or doux in the singular and douces or doux in plural are French equivalents of the English word "sweet." Context makes clear whether feminine (cases 1, 3) or masculine (examples 2, 4) genders suit. The respective pronunciations will be "doos" in the feminine and "doo" in the masculine in French.
fond memories are translated 'de doux souvenirs' in French.
It is doux in the masculine, douce in the feminine, for things that are naturally sweet. Artificially sweet is sucré(e) "sugared."
Bref et concis is a French equivalent of the English phrase "short and sweet." The masculine singular phrase translates literally as "brief and concise" in English. The pronunciation will be "breh-fey ko-see" in French.
"rêve doux belle" is not proper French. This is a software translation from the English "beautiful sweet dreams".
"Good evening! I love you, baby! Sweet dreams!" is an English equivalent of the French phrase Bon soir! Je t'aime, bébé! Doux rêves! The declarative/exclamatory statements may be heard said by a female or a male. The pronunciation will be "bo swar zhuh tem bey-bey doo rev" in French.
For a woman: "Douce, mais folle" For a man: "Doux, mais fou"
Douce in the feminine and doux in the masculine are literal French equivalents of the Italian word dolce. The singular adjective translates into English as "gentle," "nice" or "sweet" according to context. The respective pronunciations will be "doos" and "doo" in French and "DOL-tchey" in Italian.
= = doux rêves =sweet dreams
'sweet' would be called 'doux / douce' in French. This is a good term for sweet dessert wines ("un vin doux") and baked desserts, unless they are really sugary (sucré / sucrée)
doux (sweet) is pronounced like the English verb 'do'