Each Dashboard which is created or imported (Refer section Importing custom Dashboards) have their particular links which can be shared with users via mails or messages.
These links appear in the middle pane for the selected dashboard. Links can be shared for the ease of sharing dashboards to bulk users.
The links can be copied by clicking on Copy Link button which can be pasted anywhere to be shared. You can also use this link to view how your dashboard looks by copy pasting it in any browser before sharing it with other users.