A hegemon can be described as a leading or major power mostly Economy, military or politics. For example the United States has long been a hegemon in world politics and the economy.
A country gains hegemonic power due to the following reasons
Coalition: A country gains hegemonic power by building alliances or partnership through coalition this enhances its leadership and influence over others without the use of force like the United States formation of NATO, United nations and IMF.
With this they can build a common goal and also shape international norms and act as the first line when settling international disputes between nations.
Influence: A true hegemonic power must have influence over other Nations they must be able to shape decisions and and also influence the view of other countries especially those countries that are allies with them.
Military: the United States is a very good example of how a global power can show its dominance through military the United States have several military bases throughout the world and also control military alliances like NATO. Where they are in control and other countries especially the western countries depends on them for military support.
Threats: A hegemonic power can at any time use threats like tariff and sanctions to influence other countries political decisions and even use positive threats like withdraw a country access to loans and block them from accessing the international market or even withdrawing aids.
With the hope that this pressure will change the country decision to go in the direction the hegemon wants.