With accent marks:
Как ау́кнется, так и откли́кнется.
What goes around comes around.
As you treat others, so they will treat you.
This proverb is hard to translate literally. "Аукнется" comes from the sound "ау" that Russian people use to find each other in a forest. "Аукнется" is only used in this proverb, you don't find this word anywhere else. So a close to literal translation can be as follows: as you say "ау", you will receive the same response back.
Other Russian proverbs
An old friend is better than two new ones.
Make a fool pray to God - he will break his forehead.
What you will sow, that you will reap.
Fear has big eyes.
A bird is visible by its flight.
Poor people are inventive.
Free cheese is only in a mousetrap.
There are no friends for taste and color.