What does this code do

Questions
1

files = Import[“~/blog/faces94/male”][[1 ;; -1 ;; 30]];
faces = Map[Import[“~/blog/faces94/male/” <> #] &, files];

I can’t find any documentation that explains how to use Import in this way.
I’m trying to use the notebook from this website: Eigenfaces, for Facial Recognition || Math ∩ Programming

The github page is here: GitHub - j2kun/eigenfaces: Mathematica notebook and resources for the post "Eigenfaces" · GitHub

2

files = Import[“~/blog/faces94/male”][[1 ;; -1 ;; 30]];

The call Import["~/blog/faces94/male"] reads the names of all the files in the folder ~/blog/faces94/male. Then they filter it out using [[1 ;; -1 ;; 30]]; which I find strange way of doing it. I do not know why they did not use FileNames[] for this part.

SetDirectory[NotebookDirectory[]];
dim = {200, 180};
files = Import["faces94/male"][[1 ;; -1 ;; 30]]

5305Untitled.png
5305Untitled.png1142×326 11.5 KB

faces = Map[Import["~/blog/faces94/male/" <> #] &, files];

This line imports each image from the list of the files from the above operation. Now all these images are stored in faces list

faces = Map[Import["faces94/male/" <> #] &, files];
Length[faces]
 (*76*)