The SEO toolkit inside Plesk provides you with the following:
Search engine with the most rankings for your domain
Keywords you rank for
Overall number of rankings
Overall visibility of your site
Plesk also has SEO Advisor tool which will provide you with a to-do list, to help you rank better on SERP. It will give you a list of items to optimize your website as per the latest SEO standards including header tags, duplicated content, etc.
The base toolkit has a limitation on the number of keywords, but upper tiers can be purchased.