How FFT works in a signal?

I have read the MATLAB help section. But I am not totally clear what the "fft" comand really does to a signal. Could anybody please explain this to me?

Answer 1

[Star Strider]

I am not certain what you are actually asking.

The Fourier transform decomposes a signal into a series of sine functions of different magnitudes, frequencies, and phases. The output are the magnitudes and phases of each frequency component. These are calculated as complex constants that can be expressed as magnitude and phase with, for example, the MATLAB abs and angle functions.

The fast Fourier transform takes advantage of the mathematical characteristics of the sine function to significantly reduce the number of computations involved.

Answer 2

[Azzi Abdelmalek]

That's what FFT do https://en.wikipedia.org/wiki/Fast_Fourier_transform