see the id Magento take the last word after ':: ' here is modulename and add the name to li html parent of a tag the class result is class='item-modulename parent level-0'
As I assumed and as Vitalii confirmed in the comments, the IcoMoon App is used internally by Magento frontend developers to generate the custom fonts file.
Best Answer
1. Create Icon
By default, Magento 2 add a custom default icon for your module.
But you can add your custom icon to your custom admin module menu.
Create custom icon .svg with Inkscape software (open source soft for
creating vector try man !).
Create font icon of that .svg icon with help of IcoMoon.io
Go to
lib/web/fonts
create your module folder. example
Package
and paste all files obtained/exported from IcoMoon.io.Package_Modulename
go to app/design/adminhtml/Magento/backend
create folder with name Package_Modulename/web/css/source/
Create
_module.less
file under the source folderIt will seem like
Package_Modulename/web/css/source/_module.less
Now inside your file _module.less add this lines :
item-modulename : here
modulename
is comes frometc/adminhtml/menu.xml
see the id Magento take the last word after ':: ' here is
modulename
and add the name toli
html parent ofa
tag the class result isclass='item-modulename parent level-0'
For more step by step understanding, you can refer to http://ibnab.com/en/blog/magento-2/magento-2-backend-how-to-create-custom-menu-in-admin-and-change-default-font-icon