anthem (national)
The Spanish word 'himno (nacional)' translates to 'anthem (national)' in English. This word often refers to a rousing or uplifting song identified with a particular group, body, or cause, and in this specific context, it refers to a country's national anthem, which is a patriotic song officially adopted by a country as an expression of national identity.
The national anthem of Spain does not have an official lyric.
In this sentence, we are talking about the national anthem (himno nacional) of Spain. The important information is that it does not have official lyrics, which is unique among most national anthems.
We all stood up when they started to play the national anthem.
The sentence is speaking about a common practice in many countries where it is a sign of respect to stand when the national anthem (himno nacional) is played. This gesture is usually practised in formal events or public gatherings.
Study the national anthem well for the citizenship test!
This is an imperative statement telling someone to study the national anthem (himno nacional) very well as it will be included in the citizenship test. This suggests that knowledge of the national anthem is important for passing the test.