Making a digital TV out of cinema display
The answer is that it depends on what you have at the moment.  If you just have a cable outlet in the wall and the cinema display then yes you need something in between such as a tuner.  The type of tuner will depend on the type of signal being sent by your cable TV provider (digital/analogue).  Then you'll need a cable which will connect the tuner to the cinema display and you'll also need separate speakers.  This also means that your tuner will have to have an audio outlet to connect to the speakers.

With a standard analog TV signal, the TV itself is the tuner.  With a digital signal the tuner can be built into the tv or it can be in a set-top box.  To make the cinema display function as a TV you need to have a digital signal and then you need a set-top box which would allow you to change channels.

To recommend specific tuners etc. you would have to describe specifically what your cable TV connection is and how you are expected to connect it to an ordinary TV.  Then you can work on figuring out how to connect the cinema display which is just like a digital TV with no speakers and no remote.