All countries are exposed directly to the sun.
The equator is an imaginary line which is equally distant from the North and South pole. It is the division between the north and south hemispheres of the Earth.
The Earth spins at a certain angle (23.44°), but the equator doesn’t make it hot. If the Earth was to spin at a different angle, the equator could be very cold. The planet Uranus is like that (82°). It just so happens that the angle the Earth spins also makes the countries along the Equator hot.
Regarding the whole solar system, most planets have hotter Equators. That’s because the whole solar system was originally spinning in approximately the same direction.
