Earth travels 940 million kilometers every single year.
Earth revolves around the Sun in an oval shape called an Ellipse. It takes 365.25 days to finish one lap.
That ".25" at the end of the year adds up! Every 4 years, those four quarters become one full day (February 29th) to keep our calendar in sync with the stars.
During the Summer Solstice, your hemisphere is tilted toward the Sun. The rays hit the ground directly, concentrating heat in a small area.
During Winter, the same amount of sunlight is spread over a much larger area because of the tilt, making it feel colder.