By default, Magento 2 provides the pagination facility for the product pages, category pages, etc. It helps in easy navigation. Without pagination, the page load time increases.

The default Magento 2 does not provide pagination for a custom collection.

To add pagination in Magento 2 with a custom collection

create a block file in your module :

<?php
namespace MagemonkeyGeneralBlock;

class Monthlyspecial extends MagentoFrameworkViewElementTemplate {

private $_objectManager;

public function __construct(MagentoCatalogBlockProductContext $context,
MagentoFrameworkAppConfigScopeConfigInterface $scopeConfig,
MagentoFrameworkObjectManagerInterface $objectmanager,
array $data = []) {

parent::__construct($context, $data);
$this->_isScopePrivate = true;
$this->_objectManager = $objectmanager;
$this->scopeConfig = $scopeConfig;

}
protected function _prepareLayout()
{
parent::_prepareLayout();
if ($this->getMonthlySpecial()) {
$pager = $this->getLayout()->createBlock(
'MagentoThemeBlockHtmlPager',
'monthlyspecial.history.pager'
)->setAvailableLimit(array(12=>12,24=>24,36=>36,48=>48,52=>52))
->setShowPerPage(true)->setCollection(
$this->getMonthlySpecial()
);
$this->setChild('pager', $pager);
$this->getMonthlySpecial()->load();
}
return $this;
//return parent::_prepareLayout();
}

public function getPagerHtml()
{
return $this->getChildHtml('pager');
}

Public function getMonthlySpecial()
{
$page=($this->getRequest()->getParam('p'))? $this->getRequest()->getParam('p') : 1;
$pageSize=($this->getRequest()->getParam('limit'))? $this->getRequest
()->getParam('limit') : 12;

$cateinstance = $this->_objectManager->create('MagentoCatalogModelCategoryFactory');

$allproduct = $cateinstance->create()->load(0)->getProductCollection()->addAttributeToSelect('*')
->addAttributeToFilter('manager_special', 0)
->addAttributeToFilter('email_special', 0)
->addAttributeToFilter('status', 1)
->addAttributeToFilter('visibility', 4)
->setOrder('price', 'ASC');

$collection = $allproduct;
$collection->setPageSize($pageSize);
$collection->setCurPage($page);
return $collection;
}
}

create a view phtml file where you use pagination in your module

Just call getPagerHTML() code as per shown below.

<?php echo $this->getPagerHtml() ?>

<?php

$allproduct = $this->getMonthlySpecial();

<div id="layer-product-list">
    <div class="toolbar toolbar-products">
        <div class="pages">
        <?php echo $this->getPagerHtml() ?>
        </div>
    </div>      
    <div class="category-products products wrapper grid products-grid">
    <?php foreach ($allproduct as $key => $productdata) {
    	//add code for your data in loop
    }
    ?>
    </div>
</div>