META tags are included in the section of the html code that makes up a web page. They include both a description and a keywords variety. In the past, it was, in part, these tags that told the search engine spiders what a website is about, helping them to categorize properly the website within their databases.  Because of rampant abuse of these tags by spammy sites, the major search engines do not place the importance they once did on these tags in determining the placement of sites.
To view your html code and determine if you have META tags in place, simply right click on your web page and choose "View Source." This will open a separate window with the source code of that web page. The tags, if they are there, will be up at the top between the and tags.
In terms of SEO, meta tags are much less important than they once were in determining your site's place in the SERPs. The description tag is still good idea for a number of reasons; mainly that Google uses, at times, the META description tag as its description of the website within the SERPs. If no description tag exists for a site, Google defaults to the first text it finds on the page or to a snippet of text that contains the search query. The first text on your page may or may not be the message you'd like to send to searchers as they evaluate which of the results links to choose.