It helps to understand how refreshable braille displays (RFBDs) get information from the device. Apple has a software called VoiceOver that enables blind and low vision customers to navigate iPads and iPhones. (The actual use of it is slightly different on the laptop, but the basic concept is the same.) RFBs depend on VoiceOver for textual and limited navigational support.
VoiceOver is more than text-to-speech software. It's a way of organizing and displaying visual information into words (spoken or in braille). Using either gestures or RFBD commands, you can navigate between different apps, read text, switch settings (e.g. spelling and grammar and menu features).