A treant after all! Excellent.
"I greet you, treant of Fangorn forest," she replies formally in the same language, and makes a gesture of respect (*). "I am Aria, a druid of the Verduran Forest circle." (Does it handle the term 'druid' as well as Rohirric did?)
"With me is Tora. She cannot speak your language; I have tongues, a translation spell, but I can only use it on myself. With your permission, I would like to cast share language on you, a spell to let you speak our language for a day, so she can join the conversation."
"The Verduran forest is on the continent we call Avistan, on the planet we call Golarion. We came here in a teleport (**) accident a few days ago. One of the first people we met was a human mage -" she's not going to call him a 'wizard' in yet another unknown language, that sounds like it would just complicate and confuse matters - "who called himself Gandalf. He thinks this is another world than Golarion entirely."
"He also told us about the danger to your forest from Saruman's tree-logging, which is why we came straight here. On Golarion, druid circles serve as the protectors of forests, and logging is one of the most common threats from human neighbours. We hope to be able to help." Logging is, in fact, the threat to the Verduran, because of its blackwood trees. If Gandalf had wanted to distract her, he'd chosen the best possible call for action to set her immediate course.
"And we would love to learn more, of your forest and these lands and this world, if you will teach us about them, and if time permits." (In her experience, treants love to talk.)
(*) Like bowing, but with your forelimbs and your tail.
(**) instantenous-translocation. What a a good language this is! (Although, 'an accidental translocation out of The Cage' might sound a bit problematic...)