Until you get a chance to use it, here is a quick pictorial that exhibits some of its characteristics. The Locals Window displays the values of all variables local to the current scope. In the Watch Window, you can enter specific variables of interest or expressions that will be evaluated and displayed. Sections of arrays can be specified and displayed so that you don't have to deal with the whole array when you only want to see a portion. Call Stack browsing is supported to quickly browse the code in the current call chain.
Most windows expose additional functionality with a simple right mouse click in that window.