Viola wants to serve her, but, finding this impossible, she has the Sea Captain dress her up like a eunuch, so she can serve the Duke instead. Viola chooses the name Cesario and secures a position as a page working for the Duke.
Explanation: In Twelfth Night, Viola dresses as the male Cesario in order to gain entry into Orsino's court. In Elizabethan England, women were not allowed to act professionally, and female parts were all performed by men, so Viola would have actually been played by a male actor, dressing as a woman dressing as a man.
