J.R.R. Tolkien was a scholar of languages as well as an author, and created several languages, most of which are only partially intact. On Elendor, our elves have many different languages, some commonly used and others only of lore. Although we RP and put dialogue in English, your Elf is speaking an elvish language.
Sindarin
Sindarin (Grey-elven) is the only day-to-day language of the Galadhrim and the default language that Galadhrim speak. When you pose dialogue in Lórien among other elves, it is assumed that Sindarin is being spoken. Note that elves who live east of the Misty Mountains (including us) speak Sindarin with a "Silvan" accent.
Bethteur
The ancestral language of the Silvans, never named by Tolkien, is called Bethteur on Elendor. Though all Silvan elves are given Fluent language skill in Bethteur (see +LANGUAGES), Bethteur is not used in everyday speech: having been replaced by Sindarin during the "Sindarization" of Lórien, it's currently a dead language of interest mostly to language scholars, as well as a purely oral language with no writing system of its own.
Quenya
The language of the Noldor, Quenya is now no more than a language of lore, rarely ever spoken. A few highly-educated non-Noldor might also speak Quenya, but for the most part Quenya is to Sindarin speakers as Latin is to English speakers: archaic, unfamiliar, ritualistic. On Elendor, all Sindar are given Fluent language skill in Quenya (see +LANGUAGES), though we encourage those who wish their Sinda to know this language to write a history which supports that knowledge. Those who do not feel their Sindar would know Quenya are welcome to RP knowing little or none of it.
Non-elven Languages
Due to our isolation from the rest of the world, non-elven languages are extremely rare in Lórien. The vast majority of us do not even speak Westron, the Common Tongue of Men spoken by almost every other culture, or know only a very few words of it. Even those rare few who know it speak it as little as possible. If you RP with a Westron speaker, make sure to pose having no idea what they are saying!
About +SPEAKing
When among other Galadhrim, do not use the +SPEAK command to speak Sindarin: this is unnecessary, as all elves speak Sindarin. However, in scenes that include non-elves, the "default language" is Westron: to speak Sindarin in these scenes you must use +SPEAK, or at least make it clear in your pose that you are speaking Sindarin rather than Westron. If you do speak a few words of Westron, you must RP it, as Westron is not a coded +language. Of course, +SPEAK can be used for Quenya and Bethteur.
Optional Vocabulary
During RP, you may see real Sindarin words mixed in with English, though doing this is by no means required at all. Some words you may encounter include: mae govannen (well met), mellon (friend, pl. mellyn), edhel (elf, pl. edhil), elleth (elf-woman, pl. ellith), ellon (elf-man, pl. ellyn), Anor (Sun), Ithil (Moon).
Taken from +EHELP THEME LANGUAGES.
