How to call static block in left sidebar in a page in Magento 2

If you want to call static block in page

Try below code :

{{block class="Magento\\Cms\\Block\\Block" block_id="block_identifier"}}

If you want to call in phtml file :

Try below code :

<?php echo $block->getLayout()->createBlock(\Magento\Cms\Block\Block::class)->setBlockId('block_identifier')->toHtml();?>

Your xml file code should be :

<referenceContainer name="sidebar.additional">
   <block class="Magento\Cms\Block\Block" name="yourblockid">
       <arguments>
            <argument name="block_id" xsi:type="string">yourblockid</argument>
       </arguments>
   </block>
</referenceContainer>

At Last if you want to call phtml with your block in cms page :

Try below code :

{{block class="Magento\Modulename\Block\Blockname" template="Magento_Modulename::templatefilename.phtml"}} 

Refer this link for more details - https://chetansanghani.wordpress.com/2015/11/20/magento2-display-static-block-in-phtml-file-cms-page/

This should work:

<referenceContainer name="sidebar.additional">
   <block class="Magento\Cms\Block\Block" name="yourblockid">
       <arguments>
            <argument name="block_id" xsi:type="string">yourblockid</argument>
       </arguments>
   </block>
</referenceContainer>