What does 30x60 binoculars mean?
When we speak about the characteristic of binocular 30x60 we mean the combination of two different features.
The 1st number, “30”, is the magnification. 30x means objects look 30x larger/closer.
The 2nd number, “60”, is the diameter, in mm, of the objective lenses (large lenses facing away from you). 60mm is slightly larger than typical all-purpose binoculars (50mm), yet smaller than specialty astronomical binos (70–80mm) or giant binos (100mm).
This particular combination of 30x60 sounds like a niche product for enthusiasts, e.g. astronomers, and perhaps dedicated field observers who expect to set up a stationary platform. 30x is unusually high magnification for everyday use, but is well-known in astronomy (although even there it’s uncommon to actually see a pair in use). Mechanically, it’s simply a standard binocular body with a pair of exceptionally strong eyepieces, e.g. 3mm focal length instead of the usual 10mm. (Corollary: You could soup up any standard 10x50 binocular to 30x50 or more by replacing its eyepieces. Some vendors offer this as a service; of course, it costs about as much as simply buying a brand-new 30x70.)
30x power almost surely means you cannot stabilize these binoculars by hand alone, so it’s meant to be mounted on a tripod (and preferably on a binocular parallelogram mount upon a tripod), not hand-carried. It’s also possible that these are image-stabilized binoculars, which uses accelerometers to sense motion and hand jitter, and mechanically deflects a crystal in the light path to counteract most (not all) of that motion. Press that big button on top to turn on the bulky stabilization electronics, and you can hand-hold binos in a moving jeep and still read street signs at 10x power, split tight double stars, or track a sparrow chasing a hawk.
In a word, 30x60 binoculars refers to the fact that the binoculars have a seemingly magnification of 30 and that the front lenses diameters are 60mm approximately 2.36″ reasonably powerful in the magnification stakes requiring quite a steady hand.