The equation for AM wave is given as:

Frequency spectrum of AM.

AM waveform consist of un-modulated carrier (Vc sinwct) lower side band, where f = wc - wm and upper side band where f = wc + wm

Amplitude of each side band is $\frac{mVc}{2}$ where m is modulating index.

If we plot freq on x-axis and respective amplitude on y-axis, we get freq spectrum of AM.

Frequency spectrum describes how power is distributed at various frequencies from frequency spectrum, bandwidth of AM = 2 fm