If you are wondering why the Spanish soccer players all have their mouth shut during the playing of the Spanish anthem (the Marcha Real), it’s because the anthem doesn’t have any words.
There have been various attempts during the years to add words, but it never really took off. The last attempt for the sake of the Olympic bid was a disaster. The use of the phrase “viva Espana” and “ama a la patria” (love the fatherland) was a bit too Franco for most people.
I mentioned to a Spanish friend that it was really weird not having lyrics (is there another country that does this?), but she had never thought about it as not normal.