Is there any specific advantage/usage of using HTML5
I think is useless without
The tag provides a container for content that is equivalent to a figure or diagram in a book. It can be used to group a caption with one or more images, a block of code or other content.
In other words, enables us to work more freely, realistically with images, diagrams by enabling to group them & caption one or images with a single caption.
Source: http://www.html-5.com/tags/figure-tag/index.html