function uwc_new_address_one_placeholder( $fields ) {
    $fields['address_1']['placeholder'] = 'Address Line 1';
    return $fields;
}
add_filter( 'woocommerce_default_address_fields', 'uwc_new_address_one_placeholder' );
add_filter( 'woocommerce_default_address_fields' , 'override_default_address_fields' );
function override_default_address_fields( $address_fields ) {
    $address_fields['address_1']['label'] = __('Shipping Address', 'woocommerce');
    return $address_fields;
}