The "-ocular" in "binocular" is from Latin oculus, which means "eye." The 'n' belongs to the prefix bin-, which is from Latin bini meaning "2 at a time."
18-52 means the power can be adjusted from 18 to 52 times (image is from 18 to 52 times larger than with naked eye) and 80 means the diameter of the objective lenses is 80 millimeters.
Usually the first number is the magnification (in this case 30X) and if it has a zoom from 10X to 30X it would look like 10 - 30X25. The second number is the objective diameter (in mm) of the...
The 7 is the magnification produced - it is a ratio of the focal lengths of the lens at the eyepiece and the front (objective) lens. The 50 is width of the objective lens - in millimetres.