Basically you need a passport to travel internationally but depending on where you are going you may also need a visa to enter that country. This article is saying having a Japanese passport is the most powerful because it will give you access to the most countries without the additional documentation of a visa.
yasssssssskween t1_j58tk4h wrote
Reply to comment by RedSonGamble in TIL Japan is considered the world's most powerful passport, with visa-free access to 193 countries. Singapore and South Korea are close behind with 192 countries. Syria, Iraq, and Afghanistan are the least powerful, all with visa-free access to 30 or less countries. by grandlewis
Basically you need a passport to travel internationally but depending on where you are going you may also need a visa to enter that country. This article is saying having a Japanese passport is the most powerful because it will give you access to the most countries without the additional documentation of a visa.