In English, "votive" refers to something done—in this case, something built— in fulfillment of a vow, and an "aedicula" (from the Latin diminutive of aedes, dwelling) is a small structure sheltering an altar or (in ancient Rome) an image of a household god. Thus, "votive aedicula" would be an accurate rendering of the phrase in the title. Nevertheless, I am going to use "votive wall shrine" because (1) it sounds better, (2) I didn't know there was even such as word as "aedicula" in English until it jumped up out of the OED and bit me, and (3) "edicola" in modern Italian generally refers to a street stand, stall, or kiosk. (Thus, I might foil perpetrators of really rotten translations. "Promissory newsstand" comes to mind. That is almost not a joke. I am particularly angry with some local translators at the moment, so please bear with that short rant.)
There are many hundreds of small shrines, such as the ones in the photos, in Naples, particularly in the older sections of the city—that is, Sanitŕ (the section in back of the National Museum on the way to the catacombs and the Capodimonte hill), the Spanish Quarter (the square blocks on the west side of via Toledo/Roma), and the historic center of the city (bounded by the three east-west streets of "Spaccanapoli," via dei Tribunali, and via Anticaglia). The shrines are usually found embedded in the outer walls of dwellings to face on the street, but they may also be in courtyards or in stairwells within the buildings themselves. They almost all contain a religious image—perhaps a crucifix or an image of the Madonna or a saint, and some have dates telling you when they were put in place. (They may be quite recent; this is still quite a living tradition.) They are usually clean and well-maintained and may contain flowers and votive candles. There is usually an inscription saying that the shrine was erected "per grazie ricevute" (for grace received) or ex voto--in fulfillment of a vow.
Shrines are certainly not new, nor are they confined to Christianity, much less the city of Naples, itself; yet, their abundance in Naples is noteworthy and apparently has a precise historical origin. Gregorio Maria Rocco (1700-1782) was a Dominican friar known as a patron of the have-nots and who was apparently the prime mover in convincing Charles III of Bourbon to start building the massive (and never finished) Albergo dei Poveri (the Royal Poorhouse) in Naples. Rocco's other claim to fame in the history of the city, however, was the institution of precisely this tradition of shrines illuminated by oil lamps and candles in order to take back the dark alleys of mid-18th-century Naples from petty thieves, who were in the habit of stringing rope at ankle level across the way in order to trip their victims. At first, Rocco got the king to approve a number of straight good-old government-issue oil lamps. Ho-ho.They were promptly destroyed by thieves. Then, banking on the Neapolitan respect for and devotion to the saints of the city, he encouraged people to put up illuminated religious shrines.
Tradition says that the institution of these shrines, in fact, did make the streets safer at night; the collective candlepower of all the shrines made it easier to see where you were going, and perhaps the "spiritual light" worked its will, as well. Even thieves —ever devout—were reluctant to violate the Seventh Commandment with the Virgin Mary staring down at them.