The High Elves in J.R.R. Tolkien’s legendarium speak Quenya, one of his best-developed Elvish languages.
Quenya is associated especially with the Ñoldor and other High Elves. Tolkien modelled aspects of its sound and structure on languages including Finnish, while also giving it its own grammar, vocabulary, and historical development.
Sindarin is another major Elvish language, but it became more commonly spoken among Elves in Middle-earth. Quenya often has a formal, literary, or ceremonial role in the stories, and many famous names and phrases use it.
The distinction is important because Tolkien did not create one single Elvish language. His legendarium includes several related languages, and their historical relationships are part of the depth of his invented linguistic world.