Engineering affects virtually every aspect of our lives. From the vehicles that take us to work, to the buildings in which we make our living and the satellites that enable you to read this on the internet. All of these things are the work of engineers.
The key areas that engineers work in are civil, mechanical, electrical, chemical and manufacturing and the area in which you work will largely be determined by the area of engineering that you have studied for.
The areas are generally pretty separate, so picking the area that is right for you is the first step to a long and successful career.