She breathes life and hope back to Frodo.
Let's first remember where Galadriel came from: born in Valinor, land of the Gods, while both trees Telperion (the silver tree) and Laurelin (the golden tree) were still untouched by Ungoliant (from which Shelob is a descendent). This was during the First Age, thousand of years before the Third Age and the war of the Ring.
By nature, almost all elves from that period were considered as blessed with great gifts and some measure of power, be it through craft, warfare, wisdom or intellect.
She also later received Nenya, one of the three Rings untouched by Sauron's evil, whose power was preservation, protection, and concealment from evil.
At this point, her powers were a match for Sauron himself. For instance, when the White Council finally agreed (well, Saruman especially) to take care of Dol Guldur, she was there to assist and lead the assault herself. She repels even the scrying eye of Sauron from Lothlórien and his armies never encroached deeply while she was in command.
Peter Jackson shows us how powerful she can be: even on the doorstep of Mordor, she can assist Frodo and give him the nudge he needs.
There is no teleportation: only mental and psychological help from afar.