The For Each action loops over a set of collections of items, setting a variable to each value and executing the contained actions.
It is one of several Actions that loop through a set of other Actions until some criteria is met.
Whenever you need to deal with a list of things (lines, files, volumes, numbers, etc), the For Each action is a good place to start.
You can break out of the loop, retry this iteration, or skip to the next iteration with the actions:Redirect Control Flow actions.
Example #1: Split text into lines or substrings
For a complete macro using this Action, see MACRO: [FILE] Process Lines in Text File
Example #2: Get Capture Group for Multiple Matches