What can I reach more places, and the map and see more sectors?

Some parts of the map are not yet discovered, therefore you'll need to unlock them. If you see a Watchtower, you can check its description where it will say that you need to access it. Once you do, that sector of the map will be unlocked, therefore providing you with more areas to explore.

Other areas on the other hand that are far will require you to have a vehicle. An example of this is Oak Bushes, and you need a transport vehicle to get there. You can make these using your blue prints. Once you have better transport vehicles, you'll also be able to go to more places.