AF-S NIKKOR 28-300mm f/3.5-5.6 ED VR

"The other notation is an indicator of the type of specialized glass used in the lens," he added, showing me an AF-S NIKKOR 28-300mm f/3.5-5.6 ED VR.

The AF-S NIKKOR 28-300mm f/3.5-5.6 ED VR features ED glass and a variable aperture.
The f/stop changes from f/3.5 at the 28mm wide-angle focal length, eventually
reaching f/5.6 at the 300mm telephoto end of the range.

VR means Vibration Reduction

"ED means extra-low dispersion glass—it's an optical glass Nikon developed for correction of chromatic aberrations. If the lens features both Nano and ED, the ED designation moves down to a part of the descriptor text—that's the line below the Nikon name and the indicator window."

Then he took me through that line for the 28-300mm lens.

"AF-S is for the silent wave motor used in NIKKOR lenses for fast, accurate and, as you'd expect, super quiet AF operation. Next, the word NIKKOR—no explanation necessary.

Then comes the focal length of the lens. Here it's the range of this particular zoom—28-300mm. Then comes the maximum f/stop—the largest opening of the diaphragm of the lens. on this lens there are two numbers—3.5 and 5.6, which means it's a variable aperture lens: the f/stop varies as you zoom the lens. The f/stops are always indicated as fractions on the lens, by the way—that's why you always see them start with a 1, like 1:3.5-5.6. 

"Finally, we end with the letter G, which indicates that the lens has an electronic diaphragm control, meaning that the f/stop is set from the camera.