Being the president of a company can look many different ways. Did you found the company? How large of a company are we talking? Is stock in your company traded on Wall Street, or are you leading a private firm that works more locally?
Either way, being president (which is often paired with CEO duties) means your company is large enough to require a board of directors. You're in charge of communicating the organization's broadest vision to other key players and on down the line to managers and employees. You need to think big, communicate clearly, and listen well. The decisions you make affect everyone.