Complex sentence: Trương Tấn Sang (born on 21 January 1949) is the president of Vietnam and one of country's four "key leaders," along with General Secretary Nguyen Phu Trong, Prime Minister Nguyen Tan Dung, and National Assembly Chairman Nguyen Sinh Hung.
Split into simpler sentences: Trương Tấn Sang (Born on 21 January 1949) is the president of Vietnam and one of the country's top leaders. The other "key leaders" are given as General Secretary Nguyen Phu Trong, Prime Minister Nguyen Tan Dung, and National Assembly Chairman Nguyen Sinh Hung.