Bridging is using THC_SS to communicate for an x amount of time with some other module. What it basically does is firing up another module and extract data it produces. It means you're simply combining two modules into one.
The possibilities are endless and you can even bridge THC_SS with itself. You'd have to be careful though and need at least a sleep(1) to make sure that THC_SS tasks are binded properly to each other. The reason for that is that tasks are identified by timestamp and module name.
In order to do this you need to create a callback that communicates with some other module, you basically need to send a post request to the screen file of that module and get the response.
There will be a tutorial on this that will explain how to code such a callback, this is just the documentation that explains what bridging is.