In simple words, Meta tags tell the search engine the details and description about your blog or website to the search engine. It provides details like the keywords present in the page, content on the page, when the particular page was created etc.
Many search engines use Meta tags to index websites and also in their search algorithms.
You can see that Meta tags help in improving the search engine optimization of your website and hence it will help you to get more organic traffic coming from search engines.
To learn more about Meta Tags, how to use it and how it works, I would suggest you to go through the following resource by our Webmaster Tony sir where he has clearly mentioned it.
"Winners don't do different things, they just do things differently"