If you have not modify your dashboard the Yoast SEO plugin widget will be visible.

Below are your published posts' SEO scores. Now is as good a time as any to start improving some of your posts!

Posts with the SEO score: Needs improvement	1
Posts without a focus keyphrase	4
Latest blog posts on Yoast.com
Where SEO and UX meet on your site
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SEO and UX have a lot in common. They serve the same goal: To optimize the experience for search engines and your users. Learn more!

Yoast SEO 20.2: Improving our database system
(Opens in a new browser tab)

Yoast SEO 20.2 comes with enhancements to our database system powered by indexables. Find out what's new in today's release!

Read more like this on our SEO blog
(Opens in a new browser tab)

if you can not find the widget. the reason might be that you not have it active. Follow the steps to activate it. 
Click on "Screen Options"

then to activate check  "Yoast SEO Posts Overview" box

Latest blog posts on Yoast.com
Where SEO and UX meet on your site
(Opens in a new browser tab)

SEO and UX have a lot in common. They serve the same goal: To optimize the experience for search engines and your users. Learn more!

Yoast SEO 20.2: Improving our database system
(Opens in a new browser tab)

Yoast SEO 20.2 comes with enhancements to our database system powered by indexables. Find out what's new in today's release!

Read more like this on our SEO blog
(Opens in a new browser tab)

How to find the Yoast SEO on WordPress Dashboard