"EFL" = Effective Focal Length. The angle of view that the lens has when compared to a 35 mm film camera lens of a given focal length.
Therefore, the EFL of 25 to 600 mm of the FZ200 is the focal length of the lens that you would need on a 35 mm camera to obtain the same size image frame.
The actual FL of the lens on the FZ200 is 4.5 to 108 mm. Because the sensor is approximately 1/5.55 times smaller in the diagonal measurement than 35 mm film, this 5.55 is the multiplier or "crop" factor of this camera.
Multiplying the actual focal length of the lens by this "crop factor" gives you the focal length in 35 mm camera terms. This merely serves as a common basis for comparison of lenses. It is far easier to get one's mind around this than comparing the actual angle of view of a lens, expressed in degrees!
Thus, multiplying the widest angle of the lens of the FZ200, 4.5 mm, by the crop factor of 5.55 gives you the widest angle the lens can be in terms of a lens on a 35 mm camera - 25 mm. This is a pretty good wide angle lens.
Ditto for the longest FL, 108 mm. Multiply by the crop factor of 5.55 gives you the narrowest angle of view the lens can have in 35 mm terms - 600 mm. This is a very long telephoto lens.