In Drupal 8, the node is an entity. The Drupal core class Node will provide us to create or update the nodes in Drupal 8. The below is an example of creating a node Drupal 8.
Example :
use Drupal\node\Entity\Node;
/**
* add Node
*/
$node = Node::create(['type' => $contentType]);
$node->langcode = "fr";
$node->uid = 1;
$node->promote = 0;
$node->sticky = 0;
$node->title= $title;
$node->body = $body;
$node->field_1 = $field_1;
$node->save();
$nid = $node->id(); // Get Nid from the node object.
Add translate Node
/**
* add translate Node
*/
$transNode = Node::load($nid);
$transNode = $transNode->addTranslation("en");
$transNode->title = $title_EN;
$transNode->body= $body_EN;
$transNode->field_1 = $field_1_EN;
$transNode->save();