AF

Autofocus

Note that with a Nikon lens, "AF" alone, not followed by other letters, means that it's the older type of autofocus which requires an autofocus motor in the body of the camera. It's an older, slower, noisier type of autofocus than a modern "silent wave" autofocus, which would be designated by "AF-s". It also means it's not compatible with all camera bodies, particularly smaller/prosumer ones. Note also that Nikon lenses designated "AF" but not "G" have an aperture ring, so you control the aperture on the lens itself.

(All this and more can be referenced here).

Nikkor

Brand name of the lens. Nikon still produces lenses under the "Nikkor" brand.

24-50mm

Focal length range of the lens, indicating that this is a zoom lens.

1:3.3-4.5

Maximum aperture at the wide end, and telephoto end, of the lens, respectively.

At the wide end, the maximum aperture is f/3.3. At the telephoto end, the maximum aperture is f/4.5.

The aperture relates to the effective diameter of the area of light allowed to pass through as a ratio compared to the focal length. f/2 would mean the diameter is one half that of the focal length. f/4.5 means the diameter is the focal length divided by 4.5, which means less light can pass through. Remember that it's a diameter of a round opening so halving the diameter actually divides the light coming in by 4.

In simple terms it just means how much light it lets in and therefore how well it will perform in low light situations given all else is equal.

Wide Angle

Designates that the wide end is wide enough to be called "wide angle". The is redundant since it gives the focal length range anyway.

Zoom

We already knew it was a zoom because it gave the focal length range.