"Slow Sync" Flash
Depending on your camera, you may have a “night mode”, or it may be called “slow sync flash.” These both mean the same thing, and they’re ways of letting more of the ambient light into a shot when you’re using flash, so that you don’t end up with just your subject lit, and the rest of the scene pitch dark.
Generally speaking, if you’re somewhere without much light around, and you shoot with flash on any automatic mode, the camera will give you a nice fast shutter speed to reduce the risk of camera shake, and expose for the flash. This tends to mean that the rest of the scene is pretty dark - we’ve all seen this with pictures taken at gigs, or at weddings late at night.
Night/slow sync mode usually works by letting the camera choose a slower shutter speed, so that more of the light from the scene can be picked up on the exposure, and you’ll now be able to see the surroundings better. Of course, if you’re shooting in manual mode, you don’t need any of this, because you can choose the exposure combination you want anyway, but I think it’s still worth knowing what some of this automated tomfoolery does.