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
Start taking care of the dress while it's new, and of your honor while you are young.
You see your friends in the times of trouble.
Silent means consent.
There are no friends for taste and color.
Do not look at a given horse's teeth.
Don't go to the woods if afraid of wolves.
In a quiet whirlpool, demons live.
If you like sledding, you should like to carry the sled.