This is all technically out of the scope of "classroom:, and these features were hidden away so as not to overwhelm beginners.
Anyway, essentially, do_all will explode out the current sentence and replace the "ALL" part by the contents of some location (such as the inventory, the current player location, some other location, some container), and it will also stop downstream ticks.
There is an ongoing bug (mentioned in another thread) that the "ALL" tick is being counted as a tick when it should not be. I advise strongly against using do_all. The "enable_standard_all_behaviour " which defaults to true, will handle alls without having to use do_all. do_all is a very advanced command, and easy to misuse.