Select / unSelect All

Hi
Still struggling with the execution of how to select all or unselect all

Found the explanations from @Jeff_Hager but not clear ( included below )
Anybody can “translate” this for a newbie?

Edit:
Here is a more advanced version that allows for an option to Select/Deselect All tasks at once. This version feels overly complicated for what it is, but it works. I also added an option to add new tasks, and if ‘Select All’ is selected, the new task will be added as unselected and the ‘Select All’ checkbox will become unchecked. I did discover a bug when adding a new task, where it appears to activate the action on the list item and it was setting the ParentID on the new task, even though my Add Row action wasn’t setting that column value at all. I can only assume that the list action gets triggered. To get around it, I added a Set Column action to clear the ParentID column after the row is added. Feel free to play with it. All Tasks are shared among all users, but task selections are unique to each user.

What’s your current setup? Do you have a list of rows with a boolean user-specific column?