Real answer: You can see the earth is lit up in this pic, which means it's daytime. You can't see the stars in the daylight from the ground, because the sun is bright enough to drown it all out. The view from the ISS is not any different... It's only ~180 miles from ground level after all.
You can see it as a bright dot with the naked eye. You know it's not a star or planet, because it's visibly moving. You know it's not an airplane because it doesn't blink (airplanes run strobe beacons at night, which is what you see).