I have one of those!
At one time it was the top-of-the line for US made Instamatics.
I see that you have the instruction manual too! cool!
There is a battery compartment on the bottom. Since it has a CdS exposure meter, it requires the battery to operate the automatic exposure. The "X" means that it uses the X Cube flash system so that batteries are not required to trigger the flash. It is shutter speed preferred exposure.
When a flash cube is inserted (even a used one), the aperture settings are keyed to the distance focusing of the lens. Thus, it is possible to vary the F settings based upon the distance settings. However, I think that inserting the flash cube also sets a default shutter speed, probably of 1/30 sec.
It has an Ektar lens, which is Kodak's version of the Zeiss Tessar and the front of the lens ring is actually a Series V filter holder. It unscrews. Should take great pictures, even though the film selection these days is extremely limited.
-Paul