Music doesn't always have to be understandable to be enjoyable. A good beat, a melody that pulls you in or a singer with a voice you just can't ignore are all things that make a person like a song. Personally I know all about that. My mp3 player has music on it from all over the world. I do speak bits and pieces of 8 different languages, but none of the fluently, not even my own some days. I may understand the meaning of what I am listening to, but not always what each word means. Yet, I still listen to enjoy the music each band put some much work into making.
Then again, sometimes it helps to understand what the words mean. Let me give you an example of a song that can be both understood and not depending on your personal knowledge. One of my favorite bands is a German rock band called Tokio Hotel. They started out at a very young age singing all their songs in their native tongue, but later as their popularity grew, they released two albums in English, both of which I own. The song that drew the world's attention was called Durch Den Monsun (Through the Monsoon). When it was re-released in English they changed the name to just Monsoon. Here are both versions. Watch both and see the difference between them and how enjoyable both versions can be.
Monsoon By: Tokio Hotel
Durch Den Monsun By: Tokio Hotel
You can learn more about the band at these sites.
Tokio Hotel on FB
Tokio Hotel on Twitter
Interscope (The record company they use here in U.S.A.)
Tokio Hotel's website (currently under reconstruction)