To talk about (something, someone) is 'parler à propos de' (quelque chose, quelqu'un) or even shorter 'parler de' (quelque chose, quelqu'un) in French.
"Let's talk" translated into French is "Parlons-en".
parle à = talk to
talk = discours !!
When you talk loud is "quand tu parles fort" in French.
écris-moi quand tu le pourras
Parlons ! or discutons !
Je sais parler.
Nous parlons serieux.
You can say "libre de parler" in French.
parler dans votre sommeil is the translation. This is the translation of talk in your sleep.
"mes chers" (if you talk to men) "mes chères" (if you talk to women)
You can say "C'est un plaisir de vous parler" in French, which translates to "It's a pleasure to talk to you."