There have been many questions about the fourier transform, but as far as I know, not specifically the one I want to ask.
The fourier transform converts the time domain to a frequency domain. Let's say we take a simply sine function:
Then the frequency domain may look something like this (please ignore the fact that this one is centered at $0$ which it shouldn't be):
I understand how to interpret the big bump: this is the frequency of the sine function.
However, given that we can describe the "frequency" of the sine function with one number (e.g. $2\pi$), how do we interpret all the other smaller bumps on the frequency domain?
In other words, if the fourier transform would map a sine function to 1 number, this would make sense to me. But how do we interpret the fact that the fourier transform gives non-zero values for all kinds of frequencies, even those that are far removed from the sine function's actual frequency?