Foreign nationality: refers to applying for the nationality of your country of immigration and becoming a citizen of that country after living there for a period of time.

Take the United States as an example You have to get a green card first, and then live in the United States for five years before you can apply for citizenship. Generally, developed immigrant countries are like this (although the residence time required by each country is different), but if you want to immigrate to underdeveloped countries, such as Ukraine, Nauru and other small countries, it is easier to get citizenship than to get a green card.