If you need to display a new label of the product on the list page, then you can do it via helper file.

Here I have made one extension for that.

1, First you need to create module directories on app/code.
2. Then add registration.php in app/code/vender/module/.

<?php 
MagentoFrameworkComponentComponentRegistrar::register(
 MagentoFrameworkComponentComponentRegistrar::MODULE,
 'vender_module',
 __DIR__
);

3. The next step is to add module.xml file in app/code/vender/module/etc/

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../lib/internal/Magento/Framework/Module/etc/module.xsd">
 <module name="vender_module" setup_version="1.0.0">
 </module>
</config>

4. In the final step, you need to create one helper file Newlabel.php in app/code/vender/module/Helper/

<?php
namespace vendermoduleHelper;

use MagentoFrameworkStdlibDateTimeTimezoneInterface;

class Newlabel extends MagentoFrameworkUrlHelperData
{

 /**
 * @var TimezoneInterface
 */
 protected $localeDate;

 public function __construct(
 TimezoneInterface $localeDate
 ) {
 $this->localeDate = $localeDate;
 }

 public function isProductNew($product)
 {
 $newsFromDate = $product->getNewsFromDate();
 $newsToDate = $product->getNewsToDate();
 if (!$newsFromDate && !$newsToDate) {
 return false;
 }

 return $this->localeDate->isScopeDateInInterval(
 $product->getStore(),
 $newsFromDate,
 $newsToDate
 );
 }
}

After creating all the above files, run setup:upgrade command

Then, you will able to add a new label on your override list.phtml file in product loop) as per below.

<?php $helper = $this->helper('vendormoduleHelperNewlabel');
if($helper->isProductNew($_product)): ?>
<div class="lable newlbl">
    <?php echo __('New'); ?>
</div>
<?php endif; ?>

Hope my post will helped you to enrich your Magento knowledge.