The line connecting the planet to the sun sweeps out equal areas in equal time intervals. When the planet is closer, it is moving faster.
As the earth goes around the sun, there is a rotational axis. The axis, is at a slight angle.
The angle determines the season.
We in Canada will experience summer when the point is angled towards the sun
When the axis is angled away from the sun,
Kepler’s second law states that the time intervals - say July-May, and another time interval Jan - Nov have the same area.
Since, they have the same area, the orbit of the earth is fastest in the months of ~Nov-Jan.