What is SEO title and SEO description?

What is SEO and where is it used?

SEO means Search Engine Optimization and is the process used to optimize a website's technical configuration, content relevance and link popularity so pages become easily findable, more relevant and popular towards user search queries, and as a consequence, search engines rank them better.

What is SEO title and SEO description? 

The SEO title and SEO description (otherwise known as the "title tag" and "meta description") informs Google and other search engines about what the topic of your website is about. This information also shows up in the search results for users to see, and optimizing it can help them click through to your site.