。
I memorized my lines for the play.
Literal
I [topic-は] play [possessive-の] self [possessive-の] role [possessive-の] lines [object-を] memorized.
芝居 (しばい, 'play, theater'). 台詞 (せりふ, 'dialogue, lines') — an ateji reading where the characters don't yield the pronunciation. The chain of の particles (芝居の自分の役の台詞) shows how Japanese stacks possessive modifiers.