How to put Keywords on home page

How to put <meta name="description" content=" "> and <meta name="keywords" content=" "> on the website's home page?

You can put them here: https://github.com/litecart/litecart/blob/dev/public_html/includes/templates/default.catalog/layouts/default.inc.php#L6

If you do this for each and every page, edit the controllers in pages/*.inc.php.

document::$description = 'My meta description';
document::$snippets['head_tags'][] = '<meta name="keywords" content="...">';

Example:
https://github.com/litecart/litecart/blob/dev/public_html/pages/index.inc.php

Keep in mind meta keywords are since 10 years ago no longer promoted for use by Google.