Recently i have heard about Google dance? i don't understand what is this feature for? Do you know anything about it?

What i know it is about related with Google ranking.

It is not a feature, its basically a type of ranking change of a site by google which is called Google Dance, basically there is a change in a ranking continuously from top to bottom, However, If you see frequent changes in your ranking everyday, then it is called as google dance. Basically its also a good news as your website is moving and might end up at a higher position after stabilizing.