The Canon CA-110 Compact Power Adapter is an AC power adapter and battery charger that's compatible with Vixia HF R200, R20, and R21 high-definition camcorders and the camcorders' standard BP-110 battery. The adapter connects to a wall socket via its AC cord, and the plug at the other end connects to the camcorder.
The CA-110 ships with Vixia HF R20, R21, and R200 models, so this is a replacement or additional power adapter.
When the BP-110 battery is installed in the camcorder, the CA-110 charges the battery. Without the battery installed, the CA-110 can power the camera from a wall socket.