What's Google Dance?

Hi @kusah, and welcome to SEO Forum.

First thing first, please, DO NOT POST LINKS in your very first post, as it's obvious backlinking with no added value for other members and visitors.

So next time you want to share some interesting piece, don't forget to write why it's so interesting and describe what it is about in the first place, so other forumers may decide if they are interested or not before clicking...

Now, to answer your question:

It’s the period when Google is rebuilding its rankings, and results fluctuate widely for a 3 to 5 day period.

from very first G result that popped out on query 'Google Dance' https://metamend.com/archive/education/google-dance/