A tribune was someone in the government of ancient Rome who looked out for ordinary people, in other words, an elected representative. Tribune is also a word that newspapers like, such as the "Chicago Tribune" or the "Des Moines Tribune."
There are many types of tribunes, but the earliest dates from ancient Rome. In Rome, a tribune was an elected representative of the common people. A tribune was expected to look after the interests of the people, just like our politicians today. Another type of tribune comes from the world of architecture, specifically the architecture of Christian churches. The tribune is a part of the church, often under a dome, where you can find the throne of a bishop.