It’s Wordpress SEO plugin by Yoast!
Make your site load faster by adding a caching plugin
Every time your Wordpress site is loaded or refreshed, it pings every single thing on that page (all plugins, codes, images etc). If you’d like to make your site load up to twice as fast, add a plugin like W3 Total Cache or WP Super Cache. What they do is take a picture of your site regularly (like once every 15 minutes).
And instead of pinging everything every time someone loads your page, it shows them that picture. Therefore, loading it much faster.
The drawback to this is that changes you make to your site’s sidebars or headers might be delayed in showing up. But if you empty your cache, they’ll show up immediately.