Complex sentence: Polina Sergeyevna Gagarina (born 27 March 1987) is a Russian singer, songwriter, actress, and model who will represent Russia in the Eurovision Song Contest 2015.
Split into simpler sentences: Polina Sergeyevna Gagarina (born 27 March 1987) is a Russian singer, songwriter, actress, and model. She will represent Russia in the Eurovision Song Contest 2015.