An ethical tradition is a group of things that one group of people think are right and wrong. People believe that these things are right and wrong because other people think that way and they have thought that way for a long time.
An ethical tradition can be like a set of laws because most people agree with it and only do what it says is right. However an ethical tradition is not normally written down and is not enforced by a police force.
The branch of philosophy called ethics is not the same as an ethical tradition. This is because ethics is about asking questions and not just thinking what other people think. However some ethical philosophers want to know why people follow ethical traditions. They also want to know what ethical traditions are the same for different groups of people. This type of ethics is sometimes called the science of morals.