Given the nature of data transfer used in LabVIEW (wires) one of the most useful debugging tools available in LabVIEW is the concept of "Highlighted Execution".
If you click on the light bulb, LabVIEW will slow down the execution of VI, and one or several moving dots will trace the order of execution and transfer of data will be visible and traceable by the programmer. Also, in this state, all the VI starts off dimmed and as the execution continues, the parts of code that are executed exit the dimmed state. Another very important tidbit to notice is that in "Highlight Execution" while the dots travel on the wires that are currently being executed, the actual value that is carried at the moment on that wire is also displayed. The following figure is a partial cropped part of an example code of one of the examples that are shipped with LabVIEW.
Note: the left side of the picture is executed while the right side, where a loop is about to complete execution, is...