A "second-generation America " can best be described as someone

A "second-generation America " can best be described as someone who has immigrated to America or was not born in America and then later became a US citizen.

Explanation:

When speaking of American people with respect to immigration, I had always assumed that "First Generation" meant the people who were born elsewhere and immigrated to this country. "Second Generation" in this sense means those who were born in the US from these "First Generation" parents.

But recently I started hearing people use them the other way around. They call those who were born in the US, "First Generation", because they are the first generation to be born in this country.

Someone whose parents weren't born in US.

Explanation:

It should go along those lines. This is for the A P E X test.