In tha fm radio. what is the mening of fm?

It means frequency modulation and is a better method of transmitting sound than AM (amplitude modulation). In AM, the amplitude of the radio wave matches the amplitude of the sound. If you looked at a graph of the radio wave, it would be the same shape as the sound you hear coming out of the radio. The problem is, it's prone to interference.

With FM, you don't use a particularly frequency but rather a small "band" of frequencies. Rather than increase and decrease the strength of the signal, you change the frequency of it. So, for instance, quiet sounds may be represented by a deeper tone and loud noises more shrill tones (not really, because they're not in the audible range, so I'm only using this as an analogy). This method is much less prone to interference and gives better sound.

Where I live, AM and FM will both die out reasonably soon as we've been broadcasting digitally for some years. All television here is digital and the analogue signals have been ceased.