Geography is far more than a collection of facts, knowing all the names of the fifty states and their capitals, for example, or being able to say how many countries are in Africa. There is no facet of human or societal behavior that is not affected by geography, so when we study it, we gain information and ideas that can make people and societies better.
When we know that a region is subject to earthquakes, we can build differently, to put people at less risk. When a region is mountainous, we must provide different kinds of transportation systems. When a region is very warm, many societies tend to develop quite slowly, often not becoming industrialized as cooler climes are. All of this we learn from studying geography.
Many geographical features create political boundaries, features such as mountains and rivers. The border between the United States and Mexico, for example, is the Rio Grande River. We can learn from this that changing from a natural feature as a political boundary to some arbitrary boundary for a political entity does not work out very well.
Geography also makes a great contribution to our understanding of evolution. We are fairly certain now that the reason people with lighter skin are in cooler climates is because they had to become lighter through adaptation to get the vitamin D they needed from the sun. Those who were lighter survived and passed on this mutation. Geography is what allows us to see this.
Geography helps us to make better plans for society. A factory in a rain forest is a bad idea, usually, for geographical reasons. The dampness is very bad for metal, transportation is problematic, and diseases can decimate the work force. All of this is geographical knowledge.
When we study geography and focus it on the past, it helps us to better explain the activities of earlier times. The reason the British became a great seafaring nation was because they lived on an island. The reason the French colonized North Africa is because it was not very far away. How Native Americans came to America is something we know because of geography. A great deal of human history is explained by geography.
Geography affects the most basic of mankind's activity, which is growing food. It helps us to know what can and cannot be grown in a particular climate. In the coming years, with global warming and climate change, it will probably become even more important for this purpose.
I cannot think of anything we do or are that is not somehow enhanced with some knowledge of geography!