Referring to items at a mask selling stall:
じいさんはうさぎの二個隣にあるドラえもんを指さした。
The man pointed at the ドラえもん figure ??? next to the rabbit
I'm confused about what 二個隣 means. Does it mean that the ドラえもん is two items along from the rabbit? Or there is a ドラえもん on either side of the rabbit? Or something else?
Let D be ドラえもん, R be rabbit and x be any other item. What does the arrangement look like?
RxxD?
RxD?
DRD?
???
It's RxD.
1個隣, ひとつ隣 RD
2個隣, ふたつ隣 RxD
3個隣, みっつ隣 RxxD
Numbers larger than three is possible, but the larger the number is, the less likely 隣 would be used. People use 5個離れて, ななつ先 and such instead.
You can use other counters depending on what's aligned, for example 2人隣, 3台隣, 2軒隣.
1個隣/1つ隣 is redundant because just saying 隣 usually means 1つ隣. But it's sometimes used to explicitly say something is directly adjacent.
二個隣
二個{にこ}隣{となり} is pronounced niko tonari.
The meaning is just what is explained in naruto's answer.
In my answer, I'll tell you the other important items that are not written in naruto's answer.
じいさんはうさぎの二個｛にこ｝隣｛となり｝にあるドラえもんを指した｛さした｝。
In a normal phrase, it should be written as follows:
じいさんはうさぎの二人｛ふたり｝隣｛どなり｝に居｛い｝るドラえもんを指した｛さした｝。
The pronunciation of 隣{どなり} donari is euphonically changed from 隣{となり} tonari.
In the Japanese language, when we count something including living thing we use a designated unit depending on something such as 二人{ふたり}, 三台{さんだい}, 四軒{よんけん}, 五匹{ごひき}, etc.
However, there is not necessarily a fixed unit for everything. In this case, we use "個{こ}" as a unit. To use designated unit properly is quite difficult even for adults. When we do not understand the right designated unit we use "個{こ}" in substitution for the right unit unwillingly, but this means lack of intellectual culture for the adult.
As for that "二{に}個{こ}" is used in substitution for "二人{ふたり}" in the conversation mentioned above, the writer metaphorically indicate that normal children do not have intellectual culture as adults have indirectly.
