You can choose from a selection of services to promote on your profile, but you can also add your own! Use the blank service option to name and describe your own service, so that your profile accurately reflects what you do.
Make sure your profile is in edit mode (click the eye icon to toggle in and out of edit mode). Select the "Services" tab, and click the green arrow where you want to add your service offering. Select "Blank" from the list, and then create your description.