The Global Clock

When I was studying the example (Roaming-Ralph) to study how it moves I found that it used a code (globalClock.getDt()) for movement.
after searching on the web I found only one page with summarized explanation that I didn’t understand
panda3d.org/manual/index.php/The_Global_Clock

Could someone explain what this code means?
Could someone edit the manual page and put a good explanation?
thank you all

i dont know how to make it more understandable.
it returns the time sine the last frame was drawn. using basic physic to calculated the movement since the last frame… distance=speed*time
so basically this is used to calculate how far ralph moved since the last frame.

Also helpful:
panda3d.org/apiref.php?page=ClockObject