This is a very common Italian proverb: chi la fa, l'aspetti. Literally: (he/she) who does it (should) expect it. Evidently in reference to bad actions. The verb aspettare has a primary meaning of "to wait," but also means "to expect," as in this case.
This does not necessarily imply retaliation by the victim, but would be along the lines of our "what goes around comes around." I have two objections here. I don't believe that wrongdoers always (or even usually) pay for their deeds. Or they may not pay for them in proportion: often the power or money they have accumulated insulates them from retribution. Not only that: even those who don't indulge in evil are often the victims of evil. Also disproportionately.
All in all, I think this is one of the less wise Italian proverbs.
