Thanks for reading Danh Mạnh Nguyễn!

For a directory, both the read(r) and execute(x) permissions are required to read its contents. This is true for the write permissions as well.

In short, to perform any actions on a directory like listing the contents(read), writing/renaming/deleting a file in it, we need execute (x) permissions for that user or group.

I'll update the post to highlight this particular point. Thanks again for commenting!