The requisition does a pretty good job explaining what is required but let me go a little deeper
A testbed role is about sending commands to test the hardware. There might be some connector mate/demate (maybe using a Breakout Box which would require probing the signals and ensuring that the actual output is the expected output) but most of the job will likely be writing a test plan that describes how requirements for the hardware and software will be verified and then creating commands and scripts to do that. Experience or familiarity with Python or a tool like Juptyer will be looked on very favorably.
Hope this helps, and good luck!