Shakespeare's 'Twelfth Night' explores themes of love, disguise, and gender roles through its complex characters and their relationships. The protagonist, Viola, disguises herself as a man, leading to confusion and conflict, particularly with Duke Orsino and Olivia, who are both in love with her male persona. The play ultimately challenges traditional gender roles and illustrates the absurdities of love and desire through its comedic plot and rich use of language.