A road is a long piece of hard ground which is built between two places so that people can drive or ride easily from one place to the other.

The road to a particular result is the means of achieving it or the process of achieving it.

If you hit the road, you set out on a journey.

If you are on the road, you are going on a long journey or a series of journeys by road.

If you say that someone is on the road to something, you mean that they are likely to achieve it.