As a request to repeat/rephrase:

- Russian: "э?" or "а?" ("eh?" or "a?")

- Japanese: "え？" ("eh?")

- French: "Hein?" which is a nasalized sound without an English counterpart. Pronounce "Haaaaa" then let some air go through your nose by raising your uvula/lowering the back of your tongue a bit.

This voice synth is accurate: https://translate.google.com/#fr/fr/hein%3F (click on the speaker at the bottom left of the text box).

Edit: It's pretty close to its portugese counterpart: https://translate.google.com/#pt/fr/ahn%3F

We actually say both "ahn?" and "hein?". Sometimes we also use "hein" to start a sentence (usually when you are repeating a question)

"né" is short for "não é?" which means "isn't it?"