What is a melting pod?

I think you meant a "melting pot." This refers to a country where people of many different backgrounds live together. Some countries only have one dominant ethnic group, while others have a number of ethnic groups. A good example of a country that is a "melting pot" is the United States, which has people who are Caucasian (white), African-American (black), Latino/Latina (sometimes referred to as Hispanic), Asian-American, Native American, etc.