Remove items from one list in another

I’m trying to figure out how to traverse a generic list of items that I want to remove from another list of items.

So let’s say I have this as a hypothetical example

List list1 = …

What’s the point of Perl’s map?

Not really getting the point of the map function. Can anyone explain with examples its use?

Are there any performance benefits to using this instead of a loop or is it just sugar?