The boiling point of any compound depends on the strength of inter- molecular forces. Stronger is the inter-molecular attraction, higher is the boiling point.
In butane, the molecules interact with each other through weak van der Waals forces. These weak forces can be easily overcome by supplying small amount of heat energy. Thus, they have low boiling point.
In propanol, the molecules are held together by strong hydrogen bonding. These attractive forces operating between molecules are more difficult to break and therefore higher amount of heat needs to be supplied, therefore, the higher boiling point.