I got a friend who is A white Mexican white pale with blue eyes mother is white German descendant but his father according to him is a black Argentinian, so what does that make him?
So the first thing to say is that race is a social and political construct, so it's not a real thing. But generally in the Americas you're dealing with three races - Black (people of African descent), Native (the original peoples - who are quite diverse - of the Americas), and White (people of European, mostly Western Europe, descent).
In nearly all of the countries of the Americas the definitions of this are quite fluid because of intermarrying and the long history of rape throughout slavery and colonialism during the last 400 years. So in a lot of countries people are often some mix of these three things and how they self-identify changes.
The US racial categories tend, on balance, to be more fixed than in Latin America - but not so fixed that things don't change. Typically in the US "Black" has been defined as anyone with "one drop" of African ancestry. This is shifting as the rise of biracialism as some kind of distinct race has predominated, such that people tend to think of "Black" as a person with two self-identified black parents and "biracial" as a person with at least one non-Black parent. Again - most Black people in America are ALREADY mixed, so "biracial" is not (on the level of genetics) even a real thing.
There is discourse about how the rise of "biracialism" is a way to further divide black people by creating false distinctions that serve to weaken the sociopolitical power of Black people. For instance, a lot of civil rights laws are triggered by the number of Black people in an area. If a significant number of black people suddenly check Biracial on the Census form, that "dilutes" the Black population and then takes away the protections that those people would otherwise get. It also creates and exacerbates social distance that prevents unity that could threaten the dominant power structures. From a historiopolitical perspective, biracialism is dangerous and delays collective justice.
For me, this is why I think saying one is biracial is kind of silly. There is black culture and history. There is white culture and history. There is not a biracial culture and history. There aren't biracial communities that are distinct. Typically, biracial people are raised and socialized in white communities or in black communities.
Ultimately though the experience of a Black person is tied to their phenotype and sociopolitical context