CAN as described above stands for Control Area Network and was invented by Bosch in the 1980s. It runs at a max of 1 Mbps and is widely used however is now being replaced by Flexray. Its used to connect control units together on cars and reduce the wiring bulk. It also significantly improves reliability and reduces weigth by allowing information to be shared between systems on the car.
The suitable for CAN bus description is used misleadingly to describe many car electrical parts usually be vendors who have no idea what they're selling but want to sound knowledgable.
This LED replacement bulb is suitable for CANbus. What they mean is that its suitable for a vehicle that has bulb failure monitoring. CAN helps simplify the installation of these systems, but you can still hard wire them (common in the 1970s/80s)
This works with a CAN bus carPossibly true. Some vehicles only send info like "lights on" or "ignition on" over CAN. If you've got one of these than you need a unit that has a CAN connection to work, otherwise you don't.
Be aware there is no standard "dictionary" of what messages and info is sent on CAN - it vary's by manufacturer / model / model year.
If you've got a CAN network on the car the cabelling consists of a pair of wires twisted together. It's common on luxary cars from the early 1990s and mass market in the last 10 years. It's now disappearing from luxary vehicles and being replaced with fibre optics (since 2004 / 5) and other networks e.g. Flexray, MOST, LIN, Ethernet etc. I've dealt with CAN when it was in research in 1990 and have worked with it (and its replacements) ever since. It's simple to use and nothing to be afraid of.