Meta tags are the tags that describe a page content and are present in its code. They hep search engine in indexing that page so that when someone will make query related to the information it contains, the search engine will be able to display this page.
Meta tags is so important for search engine only, users do not read meta and all that. Meta tags include meta title, meta description, meta keywords. Thus, meta tags help Google to know easily what about the page has been made for.