Add below code in function,php to list only particular count product in product list page. Below code will list 12 products per page.
add_filter( 'loop_shop_per_page', create_function( '$cols', 'return 12;' ) );Use below code to list “All products” in one page. So, URL should have “URL?showall=1”
if( isset( $_GET['showall'] ) ){
add_filter( 'loop_shop_per_page', create_function( '$cols', 'return -1;' ) );
} else {
add_filter( 'loop_shop_per_page', create_function( '$cols', 'return 12;' ) );
}