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
Free cheese is only in a mousetrap.
You can't help grief with tears.
There is no bad withouth good.
Do not dig a hole for another one, you will fall into it yourself.
Some to the forest, some for firewood.
Where it is thin, it breaks.
Each sandpiper praises its swamp.
Another's soul is darkness.