In the 1961 film "West Side Story", an American musical romantic drama, Tony (one of the main characters) notes: "the most beautiful sound I ever heard" is Maria.

Tony makes the comment several times while singing a love song. It is a love song about two people who have just met. They exchange no more than 10 lines and appear to encounter each other in a surreal, dreamlike dance sequence, so that the audience believes that they have an intimate, even mystical, connection. However, when their gymnasium dissolves into the street outside Maria’s house, Tony is back in reality. He now feels that he has to sing something real.

The only two things that Tony then knows about Maria is her name and that she’s Puerto Rican—so, the only thing he can think to sing rapturously about is her name.

Also, the sound of Maria's name provides a resonance where Tony can say it in a very loving and mature way. He can also be seen as contrasting himself as much as possible from any young male Puerto Rican Maria might later meet and find truly adorable.

More Info: genius.com