'It is a song to Elbereth', said Bilbo", and at the very end of the chapter there is a hint as to its meaning: "Good night! I'll take a walk, I think, and look at the stars of Elbereth in the garden. Sleep well!"
Bilbo remarked, "It is a song to Elbereth," and near the conclusion of the chapter, there was a suggestion about its significance: "Good night! I intend to go for a stroll and admire the stars of Elbereth in the garden. Have a good sleep!"