Hi ,

To Create a menu item ,

• Create a directory within your module named static

• Create another directory named description inside the static directory.

• Make sure that your icon image is in 'png' format and named as : icon.png

• Place the icon.png file inside the static/description folder 

module_name/static/description/icon.png

In the XML where you define your main menu, add the web_icon attribute:

Then upgrade your module.

The easiest way to create a custom odoo icon is,

Goto,

https://spilymp.github.io/ibo/

 

You can generate the icon by

• Select Odoo Version, Icon Set,

• By Clicking the web icon it will open a new tab based on the icon set you choose,
  Copy-Paste  the class and  select the background-color 
  eg:  fas fa-user-shield

• By clicking generate button it will generate the icon and can download it by clicking the download button.
  
  
  

Hope it helps,

Kiran K