Magento 2 - How to get value in "core_config_data" table

First you need to include the Magento\Store\Model\ScopeInterface class in your constructor:

protected $_scopeConfig;

public function __construct(
     ...
     \Magento\Store\Model\ScopeInterface $scopeInterface,
     ...
)
{
    ...
    $this->_scopeConfig = $scopeInterface;
    ...
}

Then in your class' method you can call the following:

$this->scopeConfig->getValue('path/of/config', \Magento\Store\Model\ScopeInterface::SCOPE_STORE);

you need to inject the an instance of \Magento\Framework\App\Config\ScopeConfigInterface in your block.

$protected $scopeConfig;
protected $storeManager; 
public function __construct(
    ....
    \Magento\Framework\App\Config\ScopeConfigInterface $scopeConfig,
    \Magento\Store\Model\StoreManagerInterface $storeManager, 
    ....
) {
    ...
    $this->scopeConfig = $scopeConfig;
    $this->storeManager = $storeManager;  
    ....
}

Then create the method getStoreName()

public function getStoreName()
{
    return $this->scopeConfig->getValue(
        'general/store_information/name',
        \Magento\Store\Model\ScopeInterface::SCOPE_STORE,
        $this->storeManager->getStore()->getStoreId()
 );
}

and call in your template echo $this->getStoreName()