The amount of people in this country that don't know that Puerto Rico is part of the United States is staggering. I highly expect that this included our president until very recently. Though I wouldn't be surprised if he still doesn't quite understand and/or believe it.
But they are, Puerto Rico is unincorporated U.S. territory. Puerto Ricans are U.S. citizens, though because this country is terrible, they don't get to vote. Our government just gets to exploit them totally and leave them to suffer when their economy goes to absolute shit. Or when they get hit buy multiple massive hurricanes.
But also, they're people. They deserve our help whether they're part of the U.S. or not. Puerto Rico has been utterly destroyed and will be without power for months. Then the people there will have to figure out how to rebuild their lives, their workplaces likely having been shut down, their homes heavily damaged, and their futures blown away in the wind.
How you can help hurricane victims in Puerto Rico
Maybe after you help the people of Puerto Rico after learning that they're U.S. citizens, you could start fighting to give them the basic rights that every other citizen of this country has. If they're ruled by our government they should get to vote in federal elections that have a huge impact on their lives. Maybe then we could have a president who believes climate change is real.