Here are some examples:
* "I voted by proxy for my grandmother." This means the person voted for their grandmother because she was unable to vote in person.
* "The CEO will be attending the conference by proxy." This means that someone else will be representing the CEO at the conference.
* "The manager made the decision by proxy, based on the employee's recommendation." This means the manager made the decision based on what the employee said, even though the employee wasn't directly involved in the decision-making process.
Essentially, when someone acts "by proxy", they are acting as a substitute or representative for another person.