Complex sentence: The main airport serving Amman is Queen Alia International Airport situated about south of Amman and is much larger than Amman Civil Airport which is a one-terminal airport that serves primarily domestic and nearby international routes and the army.
Split into simpler sentences: The main airport serving Amman is Queen Alia International Airport, situated about south of Amman. Much smaller is Amman Civil Airport, a one-terminal airport that serves primarily domestic and nearby international routes and the army.