Hello Giovanni,
You will need to add several custom CSS rules under Appearance ->Customize ->Additional CSS, e.g.:
.mphb-single-room-type-attributes li.mphb-room-type-categories::before, .mphb-loop-room-type-attributes li.mphb-room-type-categories::before, .loop-room-short-attributes li.mphb-room-type-categories::before {
content: "\f236";
}
Where mphb-room-type-categories is the “categories” class and \f236 is the Font Awesome 5 Free icon snippet. Feel free to replace the class with other elements classes and the icon code to the one you need from the following list: https://fontawesome.com/v5.15/icons?d=gallery&p=2&m=free.
Regards,
Andre