Quenya was the Tolkien language primarily inspired by Finnish.
Tolkien developed Quenya as the high or ancient language of the Elves, especially the Ñoldor and other Elvish groups connected with Valinor. Its sound and structure were strongly influenced by Finnish, a language Tolkien admired after encountering the Kalevala.
Quenya was not simply Finnish with fantasy vocabulary. Tolkien created its grammar, vocabulary, history, and internal dialect development as part of a broader linguistic mythology. In his stories, it functioned as a prestigious literary and ceremonial language rather than the everyday speech of most Elves in Middle-earth.
Sindarin is the other major Elvish language and was influenced largely by Welsh phonology. Readers sometimes treat Quenya and Sindarin as interchangeable, but Tolkien gave them different histories, speakers, and roles within his invented world.