Can Someone Explain me the below PHP Code?

Please, Anyone, explain to me this condition, I did not get it. Code is Properly Working, But I forget what logic I used to return the value.

$chkBlock = Blocked::where("block_username","=",Auth::user()->username)->where("user_username","=",$username)->count();
        if ($chkBlock > 0) {

      return \Redirect::back()->withSuccess( 'This User Block you' );

        }

via Chebli Mohamed