Magento has a feature to define between 1 and 4 fields, how much do you want to use in the street field?

I’ve activated 2 fields and would like to add a label for 1 field. I have done this on the checkout shipping address page which you can see in the image below:

I just do rewriting checkout layout on di.xml :

<type name="MagentoCheckoutBlockCheckoutLayoutProcessor">
    <plugin name="rewrite-street" type="VendorModuelNameModelCheckoutLayoutProcessorPlugin"/>
</type>

And create a new LayoutProcessorPlugin.php file at VendorModuelNameModelCheckoutLayoutProcessorPlugin.php path:

<?php
namespace VendorModuleNameModelCheckout;

class LayoutProcessorPlugin
{
    /**
     * @param MagentoCheckoutBlockCheckoutLayoutProcessor $subject
     * @param array $jsLayout
     * @return array
     */

    public function afterProcess(
        MagentoCheckoutBlockCheckoutLayoutProcessor $subject,
        array  $jsLayout
    ) {
        $jsLayout['components']['checkout']['children']['steps']['children']['shipping-step']['children']
        ['shippingAddress']['children']['shipping-address-fieldset']['children']['street'] = [
            'component' => 'Magento_Ui/js/form/components/group',
            'label' => __('Street Address'), // You can change main label from here
            'required' => true, //turn false if you can removed main label
            'dataScope' => 'shippingAddress.street',
            'provider' => 'checkoutProvider',
            'sortOrder' => 30, // You can set short order of street fields from other checkout fields
            'type' => 'group',
            'additionalClasses' => 'street',
            'children' => [
                [
                    'label' => __('Label 1'), // Here I can set Label "Adresa" as per above image
                    'component' => 'Magento_Ui/js/form/element/abstract',
                    'config' => [
                        'customScope' => 'shippingAddress',
                        'template' => 'ui/form/field',
                        'elementTmpl' => 'ui/form/element/input'
                    ],
                    'dataScope' => '0',
                    'provider' => 'checkoutProvider',
                    'validation' => ['required-entry' => true, "min_text_len‌​gth" => 1], // You can also set "max_text_length"=> 255 in validation
                ],
                [
                    'label' => __('Label 2'),
                    'component' => 'Magento_Ui/js/form/element/abstract',
                    'config' => [
                        'customScope' => 'shippingAddress',
                        'template' => 'ui/form/field',
                        'elementTmpl' => 'ui/form/element/input'
                    ],
                    'dataScope' => '1',
                    'provider' => 'checkoutProvider',
                    'validation' => ['required-entry' => false, "min_text_len‌​gth" => 1],
                ],
            ]
        ];
        return $jsLayout;
    }
}

You can do this in any existing module.