The greeting “Elen síla lúmenn’ omentielvo” is in Quenya, a fictional language created by J.R.R. Tolkien.
Quenya is one of Tolkien’s most developed Elvish languages. He based much of its sound and structure on languages including Finnish, Latin, and Greek, while giving it its own history within Middle-earth. The greeting is commonly translated as “A star shines on the hour of our meeting.”
Quenya is associated especially with the High Elves and has a formal, ancient status in Tolkien’s imagined history. Sindarin is another major Elvish language, more widely used in many narrative settings, so the two are often confused by newcomers.
Tolkien was a philologist as well as a storyteller. He frequently built histories, sound changes, and relationships among languages before or alongside the stories that used them. His linguistic invention is therefore more extensive than the small vocabulary needed for dialogue in the published novels.