Low magnification binoculars in the range 6x to 8x are useful for viewing multiple or moving objects due to their wide viewing fields. High magnification binoculars in the range of 10x to 12x show distant objects more clearly but are difficult to hold steady or follow moving objects.
The first number in a pair of binoculars' specifications is its it's magnification. For instance 7x50mm binoculars make the viewed subject appear seven times closer than it actually is. Therefore an object 70 meters away appears only 10 meters away through the binoculars. The second number is the diameter of the objective lens in millimeters. A large objective lens lets in more light, so it is suitable for use at night time, dawn or dusk, whereas a small objective lens is only suitable for daytime use.