Bon bon typically refers to a chocolate or a truffle confection. The name comes from the French and is actually simply a repetition of the word good. To the French, it is a chocolate covered candy or truffle, often with a butter cream or fondant center. Sometimes "bon bon" merely refers to any candy, not necessarily covered with chocolate. The fictional idle housewife so often portrayed with a box of candy would probably have been eating the French style.
Yet in the US, the bon bon is distinctly different than what is meant when the French use the word. It is a frozen confection, consisting of vanilla ice cream dipped in chocolate. The word Bonbon® is the trademarked name of this confection produced by the Hershey Company. You can sometimes find this type of treat in movie theaters, where they are sold in a tube. You do have to eat them quickly or they will melt. They’re also sold in buckets, but aren’t the most popular of frozen treats.
You’d find what the Europeans would designate as a bon bon in candy stores instead of in the frozen food aisles. Several different companies like make candies with chocolate coverings and fondant, nut or butter cream fillings. When Lucy Ricardo is depicted in the famous episode stuffing chocolates into her mouth, she could be said to be eating bon bons.
The word is also subject to numerous spellings in addition to several definitions. It is more standard to see bonbon instead of separating the syllables. Even though "bonbon" is a registered name belonging to the Hershey Company, its use in Europe and especially France is so common it isn’t necessary to include a trademark sign unless you are referring specifically to the Hershey product.