add_action( 'woocommerce_before_single_product', 'variable_function', 15 );

function variable_function() {
echo 'this is the first message';
}

add_action( 'woocommerce_before_add_to_cart_form', 'variable_function', 15 );

function variable_function() {
echo 'This is a second message';
}

add_action( 'woocommerce_before_single_product', 'variable_function'.$randomn_info, 15 );

    function variable_function.$randomn_info() {
    echo 'this is the first message';
    }