Single statement containing if statement and for loop

I was reading pathlib module; and found this:

[x for x in p.iterdir() if x.is_dir()]

where p is Path object, and above line lists all sub directories under that directory.

I want to know what that above complex statement is trying to say, how both for loop and if statement are combined together and how can i make such statements by myself.

I am also wondering why that is wrapped in [].

Helps would be appreciated.