When stepping through a program in debug mode this window is used to show the value of the local variables. Local variables are variables that have been LOCALally DIMed at the current debug stack frame level. If you are the top of the stack then all variables local to the current program are shown.
You can use the Return Stack window (or U and D ) to move the current debug stack frame. This will refresh the Local Variable window to display the variables at the new stack level.
Symbols that themselves contain members have +/- next to them indicating that they are expandable. This allows you to drill in for a more detailed look.
The context menu for this window, like all variable windows, provides the ability to Inspect, Watch, Trap and Modify the variable selected.