What is the overhead instrument panel (pictured) near the front galley area of an A320? I have noticed this overhead instrument panel. It is convered by a transparent plastic lid with a small hole in the middle. Inside it has lot of switches. What is it supposed to do and who operates the same?

I couldn't find an exact picture, but the below image highlights the area where the panel is:



Image Source
(easamodul10.blogspot.com)

That panel you saw is the forward cabin circuit breaker panel. There is also an aft one.

It is used by maintenance personnel and cabin crew. For example if a toilet becomes inoperative, pulling the 'vacuum sys C/B' for 30 seconds might solve the issue.