The pages shown in the picture are exactly pages 12 and 13 of the Kino's
Journey picture book mentioned in the other answer. Here are
some photos of my own copy:
キノの旅 -the Beautiful World- 「記憶の国」 -Their Memories-,
Cover and obi
No, it is not explained.
The novels leave many of these up to the reader's interpretation. It is the same as Hideaki Anno leaving the meaning of the ending of Evangelion open (see Q#6) to the viewer's own thoughts, or in Code Geass, where a shot of the cart rider smiling (displaying some features of Lelouch) was cut out in order to make the ending more open....
From the text alone, it would seem that this is an orignal short story, titled "何を忘れたか覚えてますか？ ―Don't Forget to Forget!―", from the first Kino's Journey Artbook, Country of Memories -Their Memories- (記憶の国 -Their Memories- Kioku no Kuni -Their Memories-).
You can read the full version here.
The light novel doesn't give much context about the machine, and just describes it as a 小さな機械 (lit. small machine/apparatus).
One assume by the location ns accessories (hose) that it's for watering the garden. Since the inhabitants of this city are all hikikomori-types, it would make sense for machines to do all the work, life watering the plants.