<type name="Magento\Paypal\Model\Payflow\Transparent">
    <arguments>
        <argument name="data" xsi:type="array">
            <item name="formBlockType" xsi:type="string">
                Magento\Payment\Block\Adminhtml\Transparent\Form
            </item>
        </argument>
    </arguments>
</type>

This is a type configuration.

This configuration is for the adminhtml area. This is the area that corresponds with the Magento admin sub-application.

This configuration tells the Object Manager that when a user wants a Magento\Paypal\Model\Payflow\Transparent object that the following arguments should be used in the foo object's constructor.

• $data = [...items...];