Start by selecting the game/target window via the drop down menu. By default only windows with a title are shown. The list is sorted by CPU usage, that means the program with the highest CPU usage (which is usually the game) is at the top.
Sometimes the game window has no title or it has no window at all. If you don't find the game within the drop down menu, press this toggle to switch to process list instead.
This toggle allows you to (un)pause the target process. Pausing the target process might be useful to speed up scanning time. Or prevent values to be changed while scanning.