Creating a "Hello World" module in Magento 2 involves several steps. Here’s a basic guide to get you started:

1. Create the Module Declaration File

Create a registration.php file in app/code/Vendor/Module/:
  
<?php
\Magento\Framework\Component\ComponentRegistrar::register(
    \Magento\Framework\Component\ComponentRegistrar::MODULE,
    'Vendor_Module',
    __DIR__
);

2. Create the Module Configuration File

Create a module.xml file in app/code/Vendor/Module/etc/:
  
<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
    <module name="Vendor_Module" setup_version="2.0.0">
    </module>
</config>

3. Create a Basic Controller

Create a Index.php file in app/code/Vendor/Module/Controller/Index/:
  
<?php
namespace Vendor\Module\Controller\Index;

use Magento\Framework\App\Action\Action;
use Magento\Framework\App\Action\Context;
use Magento\Framework\View\Result\PageFactory;

class Index extends Action
{
    protected $_resultPageFactory;

    public function __construct(
        Context $context,
        PageFactory $resultPageFactory
    ) {
        $this->_resultPageFactory = $resultPageFactory;
        parent::__construct($context);
    }

    public function execute()
    {
        $resultPage = $this->_resultPageFactory->create();
        // Set title of page
        $resultPage->getConfig()->getTitle()->set(__('Hello world'));
        return $resultPage;
    }
}

4. Create a Basic Block

Create a Hello.php file in app/code/Vendor/Module/Block/: 
<?php
namespace Vendor\Module\Block;


use Magento\Framework\View\Element\Template;

class Hello extends Template
{
    /**
     * @return $this
     */
    protected function _prepareLayout()
    {
        return parent::_prepareLayout();
    }

    /**
     * getContentForDisplay
     * @return string
     */
    public function getContentForDisplay()
    {
        return __("Print what you want");
    }
}

5. Create a Route

Create a routes.xml file in app/code/Vendor/Module/etc/frontend/: 
<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:App/etc/routes.xsd">
    <router id="standard">
        <route id="hello" frontName="hello">
            <module name="Vendor_Module" />
        </route>
    </router>
</config>

6. Create the Layout XML File

Create a hello_index_index.xml file in app/code/Vendor/Module/view/frontend/layout/: 
<?xml version="1.0"?>
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
    <body>
        <referenceContainer name="content">
            <block class="Vendor\Module\Block\Hello" name="hello" template="hello_world.phtml" />
        </referenceContainer>
    </body>
</page>

7. Create the Template phtml File

Create a hello_world.phtml file in app/code/Vendor/Module/view/frontend/templates/: 
<h2><?php /** @var Vendor\Module\Block\Hello $block */
    echo $block->getContentForDisplay();?></h2>
<p>sample text</p>

8. Run the following command

bin/magento setup:upgrade

9. Output