Motion detection for normal driving is not usually recommended, but some people like it. If enabled, then the camera will only record when it sees something moving, such as when you start driving. You can hardwire the camera to be always-on, then in theory it will record all the time you are driving, and also if it sees any movement when you are parked. However motion detection can be unreliable, so it may not record continuously all the time you are driving, especially if you sit at a set of lights for a long time.
The frequency function relates to the 50Hz or 60Hz mains power wherever you are in the world. The intention is to eliminate flicker when recording video under artificial light.