This is a mnemonic for remembering most of the simple demonstrative and interrogative words in Japanese, which fall into a very nice and predictable pattern, as shown below. This is another example of the striking regularity of the Japanese language.
kore sore are dore
korera sorera arera dorera
kono sono ano dono
koko soko asoko doko
kochira sochira achira dochira
konna sonna anna donna
konna ni sonna ni anna ni donna ni
koo soo aa doo
These words all involve concepts of relative distance
not close, a-
far away, and the interrogative do-
Note that not all of these words can stand by themselves like koko or korera. The kono series require a following noun, as do the konna words. Also, according to two of my textbooks, dorera is deprecated.