What would an App be without icons? A default set of (hundreds of) icons is included in any Quasar App.
These are the Material Design Icons. You can you can read (and search for them) in the previous link.
It just differs the way you use them in a Quasar App:
No need for extra markup. Note the “underscore” character instead of a space character… this is mandatory, as Material Icons are displayed using a ligature font.