As the term suggests, on-page optimization includes those techniques that can be done on the pages of a website. On-page optimization relates to those things that are within your control – i.e. the content of your website. On page optimization techniques help the search engine crawlers read the website content. A readable site helps to show quality and will result in higher ranked web pages.
This tools used to optimize any website we call it on page optimization
Keyword: a keyword is a significant word or phrase relevant to the content of the website. Search terms are the commonly used keywords that user type into a search engine to find the web page.
So you need to research on keywords it means finding the search phrase your customers commonly use. Filtered keywords according to custom date ranges, query volume Historical trends, city/country or global and related phrases.