Complex sentence: When she was 17, she joined the Berlin State Ballet but returned to La Scala four years later in 2013, performing in Myrta in "Giselle" and Odette/Odile in "Swan Lake".
Split into simpler sentences: When she was 17, she joined the Berlin State Ballet but returned to La Scala four years later in 2013. She performed in "Giselle" and as Odette/Odile in "Swan Lake".