Meta tags are HTML code that describes a page’s content it’s a reference text/code that tells search engines and other services about your page content.It's HTML Code that helps you optimize the page for SEO purpose. Do you have a static (HTML/CSS) website? and not sure how to optimize your Title and Description tags? the tool like I have attached and you can generate code that you can copy and paste in your HTML.
Meta tag generator refers to the tool used for generating title and meta description of a website. Title and meta description are those things that you see in results on search engine pages. They appear with URL and are visible to the user. Most tools that check SEO friendliness of website also offer meta tag generator. These tools limit the title in range of 40-70 characters and meta description less than 160 characters. It also contains meta keywords of your website.