This file house the base html for the site. All js/css/html will eventually be fed into this file.
This file handles adding the scripts to the end of the body. Since we are using webpack to generate a manafest.json file, we will use Craft to read the json and get the path.
You can find the craft variables which are set in config/general.php:
'assetsManifest' => (array)$assetsManifest,
'assetsManifestLegacy' => (array)$assetsManifestLegacy,