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
Some to the forest, some for firewood.
Who is talking about what, and a lousy one about the bath.
Don't go to the woods if afraid of wolves.
An old friend is better than two new ones.
Repetition is the mother of learning.
A fisherman sees a fisherman from afar.
Do not look at a given horse's teeth.
There are no friends for taste and color.