Business analysis is the practice of analyzing a business or some element of that business to define its needs, and recommend solutions to address those needs, or simply to solve a business problem. This will help you create value for your stakeholders.
When you are thinking about business analysis, think about this outside of the IT realm. Normally you're thinking about dollars and cents. How can I solve some sort of business problem? You can probably solve the problem with a technological solution, an organizational solution, or a new marketing plan. The business analysis often relies heavily on lots of facts and lots of figures, and they use a lot of technology to do the analysis, but the actual analysis itself is more of a management function than a technical function.