what is smoothing in very basic terms
Smoothing can be done in many ways, but in very basic and general terms it means that you even out a signal, by mixing its elements with their neighbors. You smear/blur the signal a bit in order to get rid of noise. For example, a very simple smoothing technique would be, to recalculate every signal element f(t) to as 0.8 of the original value, plus 0.1 of each of its neighbors:  

f'(t) = 0.1*f(t-1) + 0.8*f(t) + 0.1*f(t+1)


Note how the multiplication factors, or weights, add up to one. So if the signal is fairly constant, smoothing doesn't change it much. But if the signal contained a sudden jerky change, then the contribution from its neighbors will help to clear up that noise a bit.

The weights you use in this recalculation function can be called a kernel. A one-dimensional Gaussian function or any other basic kernel should do in your case.

Nice example of one particular kind of smoothing:  

Above: unsmoothed signal
Below: smoothed signal



Examples of a few kernels: