What the "magnet symbol" means?

[jeamado]

Hi,
Maybe this question may sound naif: What the "magnet symbol" means as the image attached shows?

[yuri]

Hi,

You can drag and drop by holding the magnet to sort items.

[jeamado]

Ups,
yuri Many thanks!

[shalmaxb]

Came up this thread and would like to know, if this sortable behaviour could be configured for images/attachments?