Glad to see the awesome site from Styled Store theme. YOu can change the number of products on shop page simple from reading setting options.
Go to dashboard->setting->Reading->Blog post show at most-> then change the number of product you want.
Note : This will change the number of blog post as well. If you want to make change the shop page only then you can add this code on child theme functions.php: add_filter( 'loop_shop_per_page', create_function( '$cols', 'return 2;' ), 20 );