Complex sentence: The 13 states are based on historical Malay kingdoms, and 9 of the 13 states, known as the Malay states, each has a hereditary ruler as titular head of state and an executive Chief Minister or "Menteri Besar" as politically responsible head of government.
Split into simpler sentences: The 13 states are based on historical Malay Kingdoms, and 9 of the 13 states, known as the Malay States, retain their royal families. The nine "Malay States" have a hereditary Ruler as titular Head of state and an executive Chief Minister or "Menteri Besar" as politically responsible Head of government.