I'm aware that it orbits West to East and covers almost every part of the land on Earth. But what is the reason behind it not passing over Arctic and Antarctic regions?
This is because of its orbital inclination. This is the "tilt" of its orbit relative to the equator.The orbital inclination of the international space station is about 50°, so it orbits in a plane that is tilted 50° from the equatorial plane of the earth. Therefore, the highest and lowest latitudes it goes directly over are roughly 50°N and 50°S. It is in a high orbital inclination so that it can be reached from Baiknour in Kazakhstan without spending much fuel going from a high orbital inclination to a low one.