Blogger SEO: META tags are used to help google & some other search engines to index your page by the page description & the page keywords. Meta tags also helps adsenge to generate ads related to the page contents. This will increase the number of times an Adsense Ad Click (adsense CTR) on the page.
SEO Meta Tags to Blogger template: Blogger do not have any feature that can handle the meta tags smartly. So you need to fix this SEO your blogger template. First go to your Blogger Blogs Template > Edit HTML section. Click on Expand Widget Templates .
<HEAD>
<meta expr:content='data:blog.pageTitle' name='description'/>
<meta expr:content='data:blog.pageTitle' name='keywords'/>
</HEAD>
Then place the code in between <head> & </head> of your template code. 'data:blog.pageTitle' will automatically get the page title and your description & keywords will set as your page title is. This will Optimize your all blogger pages for the Search Engine.