I suspect they've used a general word because this can be many things. It might be a box of some sort in the basement of an urban building, into which the pipe feeds directly from the street, or in suburban and rural settings it might be the concrete enclosure round a hole in the ground, in front of the house/building. That's my case. I generally get to see the black and yellow salamander that lives there when I take the lid off to inspect the meter.