Define ethics and discuss what ethical communication encompasses.

Ethics is a complex topic; it encompasses "doing the right thing" even if one doesn't want to at the moment. There are certain standards for fair treatment that stand beyond law, religious practices, or social acceptance. The US Declaration of Independence sums these up for the edification of King George III and states:

We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.

The ethical treatment of others involves recognizing their human rights which extend far beyond the US Bill of Rights and into quality of life issues such as the pursuit of happiness. 
Ethical communication applies ethics to the process of communications, which in a global economy can be challenging. Ethical communication involves recognizing others' rights but also involves empathy, which is the ability to see life from another person's perspective. If a person offends another through an oversight in communication, which is entirely possible given the complexities of human culture, then that could be impinging on that other person's sense of well-being. Ethical communication requires people to become aware not just of the content of their messages but also how those messages might be received by their audience. 
A lot of lip service is paid to the concept of ethics; a person is ethical when that person's actions reflect a sense of ethics and when it is clear that the person will take ethical action even if that action requires some kind of personal sacrifice.
https://smallbusiness.chron.com/ethical-standards-workplace-11576.html

https://www.scu.edu/ethics/ethics-resources/ethical-decision-making/what-is-ethics/