Complex sentence: The Flag of Europe, or European Flag is an official symbol of two separate organizations--the Council of Europe (CoE) and the European Union (EU), when representing the latter also known as the Flag of the European Union.
Split into simpler sentences: The Flag of Europe, or European Flag is an official symbol of two separate organizations--the Council of Europe (CoE) and the European Union (EU). When representing the latter, it is also known as the Flag of the European Union.