Apart from icons available in the theme by default, you can use your own icon packs.
Go to “Appearance>Icon Manager” section. Click “Upload new icons” button and upload your icon packs.
Additional icon packs you can download or generate from your svg files using Icomoon service.
You can select free icons suggested in the app.
Or import your custom icon pack to IcoMoon service.
In Section “Preferences” give your icons pack title and leave class prefix as is.
Download your icon pack .
Upload your icon pack via Appearance>Icon Manager and refresh the page. The icon pack will appear in Icon Manager section.