Question

Kepler's second law implies what about planetary motion?

Answer 1

His 2nd law says that the line from the sun to the planet sweeps over equal areas in equal periods of time. This implies that the planet has to move faster in its orbit when it's closer to the sun (like the Earth is in January), and slower when it's farther from the sun (like the Earth is in July).

Answer 2

It implies the following thing. If you draw a vector connecting the Sun and a planet this vector will be covering equal areas in equal time spans. Say, each second, this vector covers N square meters, each 2 seconds - 2N square meters and so on