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
Living with wolves means to howl like a wolf.
Оne sees the mote in another's eye and ignores the log in his own.
One in the field is not a warrior.
Hurry to much and you will make people laugh.
Get your sleigh ready in summer and your (horse-drawn) cart in winter.
One head is good, but two ones are better.
A bad example is contagious.
We don't appreciate what we have but we cry when we lose it.