What does the French expression En francais dans le texte mean in English?

It's a set phrase that means "in French in the (original) text". When you translate something into French and there are French Words in the original text, you can add a note saying "en Français dans le texte" to inform the reader.

In casual speech it is often used as a funny way to say "in French". For instance if someone doesn't understand something someone else says (because of the use of foreign Words or slang) he might say "et en français dans le texte, ça donne quoi ?" to say "can you repeat that in French ?"
Other examples from a google search :
"Lunchbox, ou boîte repas en Français dans le texte, ..." = "Lunchbox, or boîte repas in French, ..."
"Sam & Max en français dans le texte" = "Sam & Max (video game) in French" (news about the game being translated into French)
Sometimes it can also use be used ironically to say that something is not French. For instance "elle l'a traité de «geek» (en français dans le texte)" = "she called him a 'geek' (yes in English)".