[LaPistola]

The MM numbers you see are the lenes focal length or range of.

You will know a lens is a macro as it will be advertised as so and will have the macro icon on the lens body.

The smaller the number in mm the wider the angle of view or the further away the subject will seem from the camera. So a wide angle lens would be say 10-24mm. The larger the number the closer the subject will seem to the camera (like a zoom on a point and shoot camera).

There are two different types of lens. Lens that have only one mm number ie: 50mm is a prime lens and a lens that has a range number ie: 70-200mm is a zoom lens.

Now its the number or range of numbers that determine what a lens is typically used for.

10-27mm Wide angle
27-80mm Portrait's
70-*** Telefocal (zooming in)