meaning of numpy.fft coefficients

[Joey]

the list generated by numpy is of form [ a+bi, c+di, ...]

could anybody tell me the meaning of the coefficients a and b? I am
very confused about fourier transform!

information provided by numpy reference says Ak = Sum  of a[m] *
exp{-2*pi * i * m * k / n} for m from 0 to n-1

Which part is a and which part is b and what is the meaning of each
part?

Thx in adv.