I've had Halvah in vanilla, chocolate or "marble" flavors, but never cinnamon. The most common brand is Joyva. It'll be in the middle-eastern foods section, if your supermarket has ethnic food sections.
It's sweet, rich, nutty, in the candy or candy-bar genre, sometimes found in candy-bar format, with a chocolate covering. The texture is a bit like the inside of a Butterfinger bar. If you break a bar with your fingers it will leave lots of crumbs.