Buttons allow you to link between pages (internal links), or out of the app to the rest of the web (external links).
Buttons can have a solid background color, or you can upload an image to act as the background.
You can choose whether to have editable button text, or just save your button text as part of the background image (in that case, delete the ‘button text’ field in the properties pane and the user will only see your image).