A status board shows you useful information about your business in an easy to digest way. Most business have a bunch of different functions (sales, customer service, infrastructure management, product development etc), each function has information that's useful to keep an eye on. How close are we to our sales targets? What's our customer support backlog like? Are our servers up? It's all useful information and all pointers as to the overall health of your business.
The status board pulls in the information from wherever it sits, displays it in a way that's easy to read and refreshes it in a timely manner to ensure it's always up-to-date.