understanding “item for item in list_a if …” PYTHON

Question

I\'ve seen the following code many times, and I know it\'s the solution to my problems, but I\'m really struggling to understand HOW it works. The code in particular is:

Answer 1

The list comprehension [item for item in list_a if item not in list_b] is equivalent to using the filter function:

filter(list_a, lambda item: item not in list_b)