Syayna was the Jazbinan Princess of Jazbina after the Battle of Yavin.
Syayna and Raol
Syayna's father, Lord Prepredenko, sought the aid of Luke Skywalker in rescuing her from "bandits." The bandits, however, were really local Rebel fighters with whom Syayna wished to join, including Raol. Skywalker led Prepredenko's soldiers directly to her, and she was put under house arrest. She was released, however, upon the arrival of Darth Vader, who imprisoned Prepredenko for supposedly executing Skywalker. With the help of Skywalker and of Jal Te Gniev, Syayna defeated the Imperial forces with minimal bloodshed and drove Vader away.
Syayna's name is similar to the Slavic word sjajna (сияйна) [sijajna], which has similar meaning in Bulgarian, Croatian, Serbian, etc.: radiant, effulgent, lustrous or brilliant (in feminine gender).
Many names in Vader's Quest (her only appearance) are actually words taken from the Croatian language and have the same or similar meaning in South Slavic languages.